IPhone loses playcount for only certain songs

Question

I have been having a bizarre problem ever since I upgraded to iOS 6 on my iPhone 4S. Every now and then, when I sync the phone with iTunes (running on a Windows 7 system), the play count for some songs is completely lost. The last played date/time is properly updated, but the play count disappears.
I use a smart playlist that only plays songs that have been played less than X times and which haven't been played in the last week so that I guarantee that I will go through my entire library. When my smart playlist has no songs left in it, I edit it to increase the "playcount less than" by 1, and all the songs show up again for my next pass through them. I was up to having songs played 20 times (this goes back to my first iPod in 2006), but then I noticed that some of them were showing up on my smart playlist again, When I looked more closely, the 19-20 plays were gone - the play counts were just blank. The last played was correct, though.
This was not consistent - it happened for one entire album at one time (weird, since the songs played at widely-separated times over the course of a month), but otherwise only for a few songs here and there, and they were getting lost at seemingly random times after a sync. So, I thought that maybe my play count metadata was somehow corrupt. I reset the play counts for all my music to 0, and then started over (with a playlist that only includes songs played less than one time). This had no problems for several weeks, but I just today noticed a song that showed up again on my smart playlist. It was last played on January 15th, but it has no play count even though I haven't reset them since January 3rd. There were plenty of songs played immediately before and after it on that same day, and they still show a play count of 1, but this one song shows nothing.
Has anyone else seen this? I have been relying on the play count for my smart playlist since I got my first iPod 7 years ago, but if it's not going to work any more, then that's going to cause me a real problem.

Answer 1

For what it's worth, and for the benefit of anyone else searching for this problem who comes across this thread, I think I've come up with a solution for the "resetting play count" bug, or at least the version I've been seeing.
As various people have pointed out in this thread the problem is related to iTunes Match, which I have enabled in order to have access to my whole library on my iPad. I don't use Match on the iPhone because I want to be able to control its contents with Smart Playlists.
It was incompatibilities between these two systems that lead to my problems with play counts, or Plays as Apple now calls them. No matter what I tried there were several albums and a handful of individual tracks that would keep randomly resetting their Plays to zero and thus populating themselves onto my Unplayed playlist where they didn't belong. More often than not this would happen when my iPhone had been switched off and on, or when iTunes Match was updated manually.
What follows are the only solutions I've found that seem to eradicate this problem. They're annoyingly fiddly, but I've had 100% success with them over the last couple of days.
The short version (for iTunes experts or those who want to find their own method):
Delete the problematic tracks from iCloud.
Set their Plays to non-zero in the local library.
Add them back to iCloud with a non-zero initial Plays count.
The step-by-step version using two machines (very reliable):
To use this method you will need to have two Macs or PCs running iTunes and iTunes Match; a "master" machine that holds all of your media and your main iTunes library, and a "slave" machine with an otherwise empty iTunes library linked to the iTunes Match account. An iOS device will not work for this because it won't let you delete tracks from iCloud.
It might be possible to use a Virtual Machine or even just a second, empty, iTunes library as the slave but I haven't tried this and it would be exceptionally time consuming, especially the two-libraries method with all the switching. I just used an old laptop I had lying around.
Make sure that iTunes Match is active on both machines using the same Apple ID. The slave machine, having no media of its own, should only be showing iTunes Match songs in its library.
In the libraries of both machines use the search box to find some tracks for which the Plays keep resetting. You need to be looking at the same tracks in the main library on each machine, not in a playlist. Use the Songs view so you can see as many columns as possible.
Make sure that the iCloud Download, iCloud Status and Plays columns are all visible on the master machine's library (right-click the column header and select them if they aren't).
On the slave machine, highlight the problematic tracks and hit Delete. Because the tracks aren't stored locally, iTunes will ask you if you want to delete them from iCloud instead. Confirm the deletion.
The tracks will disappear from the slave machine's library. Wait a few seconds and the tracks' iCloud Status on the master machine should change from Matched (or Uploaded) to Removed and the iCloud Status icon should change to a cloud with an X inside.
On the master machine, highlight the Removed tracks and reset their Plays to 1. If you're running Windows you can use the script mentioned in the posting above, otherwise you will have to play each track and use the scrubber control to jump to the end. Continue until each track is showing a Plays count of 1.
Still on the master machine, select the newly updated tracks, right click and choose Add to iCloud from the menu. iTunes match will report that it is "sending information to Apple" followed eventually by "waiting for Apple to deliver your iTunes Match results", and the iCloud Status will change to Waiting.
You may have to wait a while as the iCloud data is updated, especially if the track can't be matched and have to be uploaded. After a few minutes the iCloud Status for the tracks should change to Matched (or Uploaded) and they should also reappear in the slave machine's library.
Repeat for any additional problematic tracks.
The step-by-step version using one machine (potentially less reliable):
This method may appear simpler than the one above because it only uses a single machine, but in my experience it requires certain tasks to be done in a timely manner if it's to be successful and it's very easy to do the wrong thing at the wrong time or drag-and-drop the wrong file and screw things up. I prefer the two-machine method but if you don't have access to a second machine this is, sadly, the only way.
Note also that these instructions are for Windows, and will vary slightly for the Mac. For instance I believe the Show In Windows Explorer option has a Show In Finder equivalent on OSX, and the Recycle Bin is called Trash. Beyond that I have no idea as I'm not an OSX user. If you're on a Mac, be sure you know what you're doing before you try this method.
Make sure that iTunes Match is enabled in iTunes.
In the iTunes library use the search box to find some tracks for which the Plays keep resetting. You need to be looking at the tracks in the main library, not in a playlist. Use the Songs view so you can see as many columns as possible.
Make sure that the iCloud Download, iCloud Status and Plays columns are all visible (right-click the column header and select them if they aren't).
Select a problematic track, right-click and select Show In Windows Explorer. This will open a window containing the actual MP3 or AAC file (or files if there are multiple tracks that are part of the same album). Leave this window open and available.
Back in iTunes, highlight the problematic track or tracks whose files are in the Explorer window and hit Delete. In the dialog that appears, tick the box labelled Also delete this song from iCloud then click Delete Song(s).
Another dialog will appear asking if you want to move the files to the Recycle Bin or keep them. Click Keep File(s).
Wait a few seconds for the track(s) to disappear from the iTunes library. If you have another machine or iOS device linked to the same iCloud library you will see the tracks disappear from there as well.
Go to the window you opened in the earlier step and drag-and-drop the relevant MP3 or AAC file(s) onto the iTunes window. The deleted track(s) should reappear in the library with an iCloud Status of Waiting.
Using either the script method mentioned in the earlier post above, or by playing each track and scrubbing to the end, make sure that the Plays count is made non-zero for each newly added track.
It is VITALLY IMPORTANT that you do this quickly before iTunes begins to update iTunes Match with the track information. If you're not quick enough, iTunes will update the tracks in iCloud with an initial Plays count of zero and you can find yourself right back at square one with tracks whose Plays keep resetting. Trust me, I've seen it many times. If you feel you might not get all of the Plays set to non-zero values quickly enough, consider yanking the network cable out of the computer while you're doing this bit. I'm not kidding. Once iTunes starts uploading that data it's anybody's guess as to whether the Plays counts will stick or not.
Once all your Plays are non-zero, wait (plug the network back in if you pulled it!) and after several seconds iTunes will start to display a series of feedback messages in the display window starting with "Sending information to Apple" and will conclude by matching your track(s) to iTunes and uploading if necessary. These operations may take considerable time especially if there were many tracks added simultaneously. Once concluded the iCloud Status for the track(s) should change to Matched or Uploaded.
Repeat for any additional problematic tracks.
Please note that I've only used these methods to work around the intermittent resetting of Plays. For other issues raised in the thread linked above, including the loss of Last Played dates, these methods may be of limited use or no use at all but they may serve as a jumping off point for others to find their own solutions.
I've still got no idea what causes certain tracks to suffer from phantom Plays resets in this way, although I did do an awful lot of switching iTunes Match on and off on various devices when I first subscribed so it's possible I'm at least partly responsible even if it's ultimately an Apple bug that's manifesting. All I know is that for the first time in months I'm reasonably confident that my Unplayed playlist won't suddenly repopulate with old tracks.
I pray the next few days don't prove me wrong.