More playback issues with Musescore 4

I am finding that playback is so disfunctional for me that I am sticking with M3, although the sound is so much better on M4.

The enclosed score originated in MuseScore 3.

1) When loaded, the score plays correctly. However simply click on the 'repeat loop' button which places markers at the start and end of the score, then playback always breaks back to the start from the end of Bar 11, having played the first two A sections correctly. Setting playback markers in a series of bars always seems to lose the first part of the first note when the repeat starts.

2) I miss the tempo sliders from M3. That being said playback is broken when attempting to change tempo using either score editing or the somewhat hidden tempo change slider. When the playback hits a 'return to the section start' bar, it loops back and misses some bars, and in some cases will simply stop playing notes.

Try changing the tempo on this score to 120% and the playback begins to fail. It's easier to show than describe, so I've done a tiny video, which cannot be uploaded here - however - it's on my public Dropbox @ https://www.dropbox.com/s/51bedk7ng6hv8c8/Musescore4-tempo-fail.mp4?dl=0. You will have to download to see the video properly. The effect appears to be repeatable. and is made worse by increasing the tempo to say 140%.

This is all on an Intel iMac running Catalina (because Apple in their wisdom has deemed my machine to be an antique that's not worth supporting).