MuseScore 4 Staff/Part Properties: Transpose changes chord symbol, but not chord pitch

MuseScore 4: The piece has a single staff with melody plus chord symbols above staff. I can transpose the whole thing fine using "Tools" - "Transpose".

Using "transpose" the melody and chord names change correctly . They both display and SOUND the correct pitches when played on the computer. (So it seems the chord symbols are being correctly recognized as chord symbols.)

But on this same piece, when I use "Staff/Part properties" to transpose (so concert pitch is different from written part pitch) the notes and chord names change and display correctly both when "Concert pitch" is checked and when it is not. BUT ... only the melody SOUNDS concert pitch when "Concert pitch" is both checked and unchecked. The chords, though DISPLAYING the transposition correctly, also change the pitch SOUND when the "Concert pitch" is toggled.

Details:
The piece's concert pitch is D.
I changed staff/part properties to transpose staff up a major second ...
With "Concert pitch" checked I expect the piece will display AND sound "D"
With "Concert pitch" NOT checked I expect the piece will display "C" and sound "D"

But what I'm getting is:
With "Concert pitch" checked the piece displays AND sound "D" (both notes and chords)
With "Concert pitch" not checked the piece displays "C" (both notes and chords) and the melody SOUNDS "D" but the chords SOUND "C"

This piece and this setup works as expected on MuseScore 3, where it was originally written. I imported it into MuseScore 4, and got the results described above.

I wrote a NEW test piece using MuseScore 4 and am getting the same error, which suggests the problem is not with importing.