Score Editor: instruments randomly changing on their own

[philmac]

This issue is driving me crazy! I’m doing vocal scores - Soprano, Alto, Tenor, Bass, etc and it keeps switching to random instrument types.

This also come up in this thread where I document some screenshots of what I am seeing:

Random change of instrument type

I am seeing this issue regularly but more recently since I updated to 15.0.20 and 15.0.21. A few times a day the Instrument Type/Clef suddenly changes. When it happens the change is permanent. When I close and re-open the score window or the project itself, the incorrect instrument type is still selected. A clue is that the layout dialog box shows the correct Instrument Type, but when you open the dialog box the current selected one is different. Note that it should be Baritone and shows tha…