Can no longer modify track information or artwork in iTunes 12.9.2.5

Hmm, that ought not be a problem. exFAT probably would be.

Did you see the section in Repair security permissions for iTunes for Mac - Apple Community on multiple tags in mp3 files? When working with a single file are the fields greyed out to indicate that they cannot be edited, or are you able to make edits that either don't get applied, or get applied temporarily but then revert to the original values?

tt2

Where is the media stored? iTunes on Mojave seems somewhat picky about the disk formats it supports. You could update to 10.14.2 in case that helps. You may need to explicitly reset permissions even when they look OK at the top level folder.

tt2

Does using the command File > Convert > Convert ID3 tags... > None several times have no impact at all? If you view the track details in Finder then a property like Album should be deleted in the tag is removed even though the iTunes library will retain that information.

The other option is convert to a new file, which should then have an editable tag.

tt2

Mojave isn't designed to let you uninstall iTunes. I've heard of someone who has copied over a 12.6.5.3 app from another partition and it is working, but Apple clearly aren't making that easy. Can you test behaviour with a library created on the internal drive. Is the external drive case sensitive or not? It could possibly be a factor.

tt2

I have been battling with this exact same issue for weeks now. Running Mojave and iTunes 12.9.2.5 on a 27" iMac and my iTunes music folder is part of my 2TB internal Fusion Drive. I wasted the better part of an entire weekend trying all the various "fixes" found on these forums with no positive results. So frustrating!

Interestingly I found myself having to resort to using the exact same piece of incredibly overpriced software (Mp3Tag) to "correct" the tags prior to importing. The worst is if you make a mistake and don't properly correct the tag prior to importing, you have to delete the tracks from iTunes, correct them again with Mp3Tag, and then import all over again. An awful predicament for someone as anal-retentive about his music as I am. Even a simple genre correction switches back to the original import (thanks whoever decided to use "JazzReggaeLatinFunkSoul").

I cannot imagine we are the only people experiencing these same issues... is it possible most people just don't edit or don't care about correct tags once a track is imported?

See Repair security permissions for iTunes for Mac - Apple Community.

tt2

Sorry, if you're running 12.9.2.5 then you're already on the latest build of Mojave. Ignore that suggestion.

tt2

Where exactly is the media stored? What format is the drive in? Did you explicitly reset the permissions even though they seemed to be OK? I don't know when the next update will be out.

tt2

What format is the drive in? It seems iTunes on Mojave prefers HFS+ or APFS.

tt2