mp3s won't play

Not sure if this is a problem with iTunes 12.1.2.27 or iOS 8.3, but I'm having a ton of problems with mp3s. It started with album art not showing being imported into iTunes, now they just don't show up. When I sync the mp3 to my iPhone the album art will either not transfer (weather it shows in iTunes or not, many times even when they don't show in iTunes!), they will show when scrolling through songs (or playlist) but not when being played, or will show when scrolling but once played will disappear entirely until I close the music player on the iPhone but reappear when the music player is restarted.

Also song will appear and play in iTunes, but when I sync them to my iPhone i will either get an sync error or songs will simply just not sync (they show on the iPhone but in grey w/ the circle to the right). If I leave the iPhone connected for a couple of hours it will show that the songs have synced (NOT in grey and NO circle), but simply won't play on the iPhone (but still play fine in iTunes). Just a note, many of these songs have been synced to the iPhone in the past with no problems.

Am I the only one having these problems?