Muse Score 4 Piano Keyboard sound may not play

I have also experienced a problem of the piano keyboard sound, but I may have a workaround. On my score I was using the piano keyboard and entering notes manually. Everything was fine. Then I saved the score and re-opened it, but the keyboard no longer had sound. I made a change in bar 10, saved the file. Made another change in Bar 10, saved the file and closed it. Upon re-opening the file, I got no sound from the keyboard. But then I played back the first two bars of the song, stopped the playback using the spacebar, and voilà! the keyboard had sound again. I tried this on several different files, all with the same result.

This is iMac M1 chip, OS Sonoma 14.1.2