I have the latest MusicBee and used it to do what is termed Volume Analysis.
This will write an APEv2 tag to MP3 files as it uses mp3gain to analyze the files.
When I load any MP3 into Mp3tag afterward, no info is shown.
The tag info shows ID3 tags and APEv2 tags.
If I set Mp3tag to delete APE tags, then delete tags, the ID3v2 info is shown again.
These files read fine in foobar, and of course in MusicBee.