Bug when sorting by virtual tag

[AgentBull]

For compilation albums, I always tag each track's year individually because I don't want Beatles songs from a 'best of' album to have a 2016 release year, for example. Because of this, albums split up into multiple albums, so I made a custom tag 'album year' where I put the album's release year/date. In order to be able to sort all albums, regular as well as compilations, by year, I made a virtual tag 'Sort Album Year' which appears to work as intended:


Here's the bug: When sorting the Album Covers view by Album Artist / Sort Album Year / Album, I get this:

As you can see, not even the album artists are in correct order. Sometimes it changes, sometimes changing to Album and Tracks view and back will fix the album artists being in wrong order, but then albums will split up randomly (even regular albums with consistent year tags). This affects only the Album Covers view but both the Music and the Inbox tabs.

Some screeshots of my preferences:

[Steven]

the virtual tag is probably a red herring. If you check each file for the first D album, or possibly the F and G albums, one of the files will probably have a sort artist or sort album artist value.
Could you confirm that and what the value is.

[AgentBull]

The F album you can see there is actually only 1 track from the album. The rest is further down. There is absolutely no difference between the files of this album besides track title and number. Also no sort artist or sort album artist values. The same goes for all the other affected albums.

[Steven]

If you sort by Album Artist/ Album does it work?

[AgentBull]

I just realized that no sorting method works, actually. Sometimes it works at first, but as soon as I hit F5, it breaks again.

Edit: Changing to Sort Descending and then changing back has fixed the issue (for now). Even after refreshing and restarting MB, everything is displayed correctly. I still don't know what causes the issues but for the moment I'm satisfied.