Corrupted music library in iTunes 12.13.6.1

I updated and installed the latest iTunes on my Windows 11 PC. Then I synced my iPhone days later. Now about 50% of the music and album artwork are missing from the iPhone. When I check the music library against the one on my previous Windows PC, that library is intact.

The Windows 11 PC has been in service for over a year. The music library was successfully ported to this PC after it was purchased, without problems.

Also, an old iPod still has the complete library, less recent purchases. It has not been synced to any PC for more than 1 or 2 years