After a series of "unknown errors," iTunes Match is not properly connecting to my library

Question

Last March (yes, that long ago), iTunes Match mysteriously stopped accepting the input of new music to the cloud, always citing an "unknown" error, though each time the number given for the error was different. After trying a number of standard solutions (turning iTunes Match off and back on, etc.), I turned to various tech support forums and tried the various solutions offered there. Nothing worked. Eventually, I found someone who suggested holding down the "option" key while selecting "Turn Off iTunes Match" from the drop-down menu, then turning it back on. Half of the people on that forum said it worked, half said it didn't, and one person said it erased their entire library. I decided to try it, and doing so somehow severed the connection between my computer's library and iTunes Match. Here's what I mean: Once I tried this, suddenly ALL of the songs in my library (songs that were already in the cloud, songs that weren't, AND songs purchased FROM iTUNES) were now marked with the symbol meaning "waiting to be put into the cloud." I tried selecting "Add to iCloud," but it never did anything. Sometimes, it said that no new songs could be added because my cloud is full (It's not. It is somewhat close, but it is definitely not completely full), and other times it just gets stuck in the "Sending Information to Apple" stage. Oddly enough, anything that was already put into the cloud is still accessible via iTunes Match on my phone and the devices of the other members of my family (we share the same library, the "master" copy of which is on my laptop). New purchases from the iTunes store appear there as well, but none of the new manually-imported music can be entered. This is particularly frustrating since my family and I have bought numerous CDs in the intervening time, and we'd like to be able to access them. I took my computer to the local Apple Store for an appointment at the Genius Bar, and three separate people examined my iTunes library and computer, but none of them could figure out what the problem was. We tried creating a new "source folder" for the iTunes library, but we were immediately met with the same problem of not being able to put any new music in the cloud. We also discovered that, because of these mysterious problems, there was no way to remove anything from the cloud, meaning that even if it was full, there's currently no way for me to do anything about it. The only thing we were able to determine for certain is that iTunes Match is not communicating with my iTunes library, though I pretty much already knew that. They suggested I schedule a call with Apple support, but since that would cost $30 just to set up with no guarantee that they could actually help with this problem, I've decided to see if anyone else out there has any useful ideas. Any and all input would be greatly appreciated, as this has been driving myself and my family mad for several months now.

Answer 1

The grand total of songs in my library is 69839, though that includes songs purchased from iTunes as well as tracks that aren't intended for the cloud anyway. As to your other question, ALL of the songs that were in my library before the big crash show their iCloud status as "Waiting." That includes stuff that I'd bought from iTunes. I tried clicking the "Add to iCloud" option for these albums that were already in the cloud, and a couple removed the "Waiting" symbol, but most didn't. As of this past week's bizarre development, everything that was already in the cloud is now being displayed twice in my library, once as "Waiting" and once as being in the cloud but not on my computer, giving me the option to download them to my library.