I updated to the new version of iTunes on my PC and installed the latest iPhone update. Now iTunes will not sync my music to the phone. I do not use Apple Music - most of my library is from CDs I have imported

I use iTunes on a Windows 7 PC and recently upgraded to the most recent version. I also installed the most recent IOS update on my phone. Now iTunes will no longer download the songs I have in my library from imported CDs to my phone. The sync goes through "preparing to sync", "determining tracks to sync", and then just flashes the Apple logo without actually syncing. The tracks are all still there in my library and can be played on the computer, I just can't get them onto the phone. I do not use Apple Music or ITunes Match. I just want these tracks physically downloaded to the phone

I have tried all of the following:

Making sure the checkboxes on the summary page are correctly checked so that iTunes only syncs my selected playlists

Restarted iPhone (multiple times)

Restored my iPhone from my latest backup

Reinstalled iTunes

Tried an earlier version of iTunes

Swapped out the USB cable

Nothing is working. I have spent about six hours already trying to fix this issue. I have been using iTunes for over a decade and have never had this happen.