Change genre or artwork on mp3 file does not work! Whyyyyyy?

Hi guys,

This is really weird. I've been using iTunes for a decade now and I've never seen this before.

All of the sudden I'm not able to change any of the following fields on the Get Info window: genre, artist, album, year. Every time I try to change these fields they revert back to the original value. Please have a look at this little video I've done that clearly shows what happens.

However, it seems that I'm able to change the album artist and composer fields and that rules out permission settings, right?

The mp3 files I'm trying to change are all located on the internal hard disk. iTunes version is 12.9.5.5 and I've already rebooted the laptop. The iTunes library has 125K songs (2.5 TB).

Thanks in advance!

Ed