iTunes and iTunes Match users still having issues with iOS 6

Since the release of iOS 6, our forums and tip lines have been buzzing with issues relating specifically to iTunes in the Cloud and iTunes Match. Issues seem to range from iTunes Match expiration notices, sync issues with ringtones and text tones via iTunes, and slow performance when it comes to streaming music.

iTunes Match issues

iTunes Match sending out expiration notices to iOS devices even though their computer still says the subscription is valid. I've personally been experiencing this issue myself. Devices running iOS 5 seem to not have the issue. While my iPhone 5 will not load iTunes Match and tells me it's expired, my iPhone 4S running iOS 5.1.1 works flawlessly with Match. After quite a bit of time on the phone with Apple, they still weren't able to pinpoint the issue.
iTunes Match streaming slowly or many users experiencing a lot of lag when switching between songs.
Album artwork missing or not showing up on certain albums, even purchased from iTunes content.

iTunes specific issues

Syncs hanging up on Waiting on items to copy or Waiting for sync to start. We've had many users experiencing this issue, perhaps even before iOS 6. We aren't exactly sure what's causing the issue, but if you're experiencing it, let us know.
iTunes removing ringtones and text tones from devices and not syncing them back. This is another one I've personally experienced and have found many others in the same boat not only in our own forums but in Apple's support forums as well. Once iTunes removes the text tones and ringtones they don't seem to want to sync back over. The only way I've found to deal with the issue is to restore my iPhone as new and restore from an iCloud backup that contains the ringtones and text tones iTunes deleted.

We're going to start trouble-shooting them in the forums, so head on over and either start a thread with your specific issue or, if a thread already exists, add what you're seeing into it. We'll keep track of the problems and start sharing solutions. Pick a forum below, add you post, and lets crush this.