V4.0.x will randomly stop playing notes when cursor is still moving

I am converting my Musescore 3.6 files to 4.0. While attemping to playback the files (simple piano lead sheets), the system will arbitrarily stop playing some notes while the cursor is still moving.

These files all played normally when first opened, yet any attempt at modification causes these ramdom glitches. closing and reopening Musescore does not fix the problem, nor does rebooting the computer.

This problem did not exist for me in V3.6