I discovered a bug in foobar tagging files. What I discovered concerns wavpack files with apev2 tags.
One single was encoded to wavpack format. I tagged it with mp3tag. When I opened the file in foobar, I noticed that the "Album Artist" field was empty even though I added a value there.
So I decided to put the test in there for a test. After typing and opening the file in mp3 tag it turns out that foobar has made a new tag called "ALBUM ARTIST" and it should be "ALBUMARTIST". This "ALBUMARTIST" was visible in the foobar only as a separate tag at the very bottom of the list. And it should appear as "Album Artist" in the gui interface.
I use foobar2000 v1.6.12b2.
EDIT: This is properties of this file in foobar.
Artist Name : Warriorz!
Track Title : (Be My...) Energizer (Hi-Energy Euro Handz Up Mix)
Album Title : (Be My...) Energizer (2K21 Handz Up Exclusive Edition)
Date : 2021-10-06
Genre : Hands Up
Album Artist : Test
Track Number : 01
Total Tracks : 08
Disc Number :
Total Discs :
<ALBUMARTIST> : Warriorz!
Actually Mp3tag is incorrect here. The standard tag fields in APE tags use spaces. Though foobar2000 should be changed to read these alternative spellings too.
You can create a mapping (https://docs.mp3tag.de/customization/options/tags/mapping/) in Mp3tag for
Source: Album Artist
to create a field that is compatible with foobar2000.
Oh, I didn't know that. Thanks for the information.