B chord is always rewritten to B-flat ... and copied "B" becomes "H"

Issue: cannot type B chord, but only B♭ chord:
1. Load the file bb.mscz
2. Change a chord to "B"
3. Observe that it is actually "B♭"

Issue: B chord from another file becomes "H":
1. Load the file bb.mscz
2. Make a new file
3. In the new file, add a note, and make its chord "B"
4. Copy the note and chord to the bb.mscz file
5. It shows as "H"

This bb.mscz file came from an older version of MuseScore (3.02) and was modified and upgraded over time. Buggy behaviour is in version 3.6.0