I'm not really sure what happened to my app data. I backed up my iPhone 5 on iOS 8 Beta 3. I was going to OTA update to Beta 4, but I only had 500 MB left and the update required at least 2.5 GB. So, I option-restored with Beta 4 and set up my phone as a new device just in case the low storage would screw up the update. While it was restoring, the process froze, and I had to restart the restore with the phone in recovery mode. After it successfully restored this time, I then restored my backup from Beta 3 and everything transferred correctly (music, photos, settings, etc.) except for my app data. If I go into any of my apps, it acts like I never opened them before and apps that held files are completely blank. Thinking it was just a one time fluke, I restored again and even tried a different backup from that day, but the same thing happened.