Some information for the Apple troubleshooting folks if they are actually interested in trying to solve this mess for all the people experiencing this problem. If anyone else has similar scenarios or versions, this kind of information might help them to recreate and correct?:
Windows 7 Home Premium Service Pack 1
iTunes 12.7.0.166
iPhone 7 iOS 11.0.1 (when the problem occurred), now on iOS 11.0.2
This occurred after I did an iPhone sync to my iTunes on the PC. My sync settings are:
- Automatically sync when this iPhone is connected
- Sync with this iPhone over Wi-Fi
- Manually manage music and videos
I am also setup for an Automatic backup on sync to my computer with the "Encrypt iPhone backup" option selected.
The songs on the PC displayed correctly still, only the songs on the iPhone were messed up to these very long and unusual numbers like 15702895289075 or -382754089274. I'm not sure I have the length of the numbers correct anymore as I did the lengthy "delete from Library", and then reinstate the purchase and redownload solution. Was not fun for 300+ songs/albums.
One thing I remember that maybe could have thrown the library off: I introduced a regular MP3 to my library on the PC and then did a right-click from my Library "Add to Device" and selected my iPhone. It's possible this was DURING the Sync or maybe right before. I can provide that specific MP3 file if it would be helpful. It was a free download from a local radio station of a new song.
Hope that helps Apple attempt to do a recreate or troubleshoot of this issue.