IPhone 5 loses or forgets my music

Question

I had this problem several times with my iPhone 4, and now I'm seeing it again (several times over the last two weeks) with my iPhone 5.  I open up my Music Player, and all but two of the artists (one song per) are "gone" from my music library.  As a note, one song was purchased from iTunes, the second from my personal collection.  I can't testify to it, but I think they were two of the last songs to get added to my library before I started having this issue... 
When I look at the "Artist" button, I get only two bands.  When I click on the "Songs" button, I get only two songs.  If I click on the "Albums" button, I get a longer list of options.  Most of my artists with only one or two songs get lumped into an album I called "Rock".  All the artists with a song in the "Rock" album show up under "Albums", but not "Artists".  Nor are the songs in the "Rock" album on the "Songs" list either.  It appears that about 120 artists are under "Albums", since it lists each artist that's lumped into "Rock" seperately.  But that's only about half of all the artists in my library.
More than half of my 32 GB phone is music (17.5 GB), and all the music is still there as best I can tell.  When I go to Settings - General - Usage, it still shows the music to be there.  The stock Music app just can't find it.  When I had this issue with my iPhone 4 (can't remember which iOS upgrade caused it, but it was when we could first wirelessly sync with iTunes via WiFi), I could use the "Search iPhone" function and find all my music (typing "Metallica" would list all their songs, for example) and play it from there.  That's not working here anymore (and I checked, all options are selected on "Spotlight Search" within Settings).
A search of the internet showed a few people with similar problems.  The most common solution was to connect the phone to iTunes, play a song in iTunes that was also on my phone and then re-sync.  That was supposed to make the music just reappear.  Alas, it doesn't work for me.  Only solution I found that works consistently is to wipe all the music off my phone and then reload it.  At 2500+ songs, this takes quite a while.  When I started experiencing this on my iPhone 4, I eventually turned off the WiFi syncing and would only sync when the phone was hard-connected to the computer.
I have two laptops in my house as well as a desktop PC.  iTunes is only on the PC, which is only used anymore for iTunes stuff.  I do very little else with the PC, so it stays off most of the time, only turning it on when I want to add content to my phone.   I'm not sure that the WiFi sync is the problem, because last week I lost all my music mid-day and the PC was off (music was "there" while I was at work, and then "gone" when I went to the gym).
My wife had a iPhone 3G and now has a 4S.  We also have a 2nd Gen iPod Touch.  Neither of their devices has experienced this issue, but then again, I'm more active with loading and removing music from my device.  This is really frustrating, as listening to music is an important part of my day.  I know there are plenty of streaming internet radio options (and I use a couple here and there), but I don't want to burn thru my data plan because I can't listen to my music at work or at the gym.
Is anyone else having this same issue?  And are there any more practical fixes instead of clearing off my phone?

Answer 1

I found this response to the problem in the MacRumors forum:
"Syncing of music via iCloud (iTunes Match) precludes syncing of music via iTunes. This is not a bug, you simply must decide whether to use iTunes OR iTunes Match but not both, to sync music on your phone. To stop syncing music via iCloud and use iTunes to configure what is synced, on your phone go to Settings / Music / iTunes Match and turn that OFF. Then go back to iTunes on your computer, then Devices / [Phone name], select Music from the top menu, configure your sync settings, and click Sync.
"Alternatively, if you wish to use iCloud/iTunes Match to sync but only via Wi-Fi, then on your phone go to Settings / Music / iTunes Match, make sure it's on, and change its subsetting "Use Cellular Data" to OFF. However, this may prevent you from listening to your music via phone when you are away from a Wi-Fi network."
I unchecked the iTunes Match on the iPhone and the music synced fine.