Playback starts at the wrong place

This was previously logged under a post "Playback volume..." but to avoid confusion I am re-entering it here.
I create a playback loop (at any point in the score),place my cursor (select) on a note half way along the playback and hit the playback button and see the playback start at the beginning of the loop, even though the cursor was placed on a note within the loop. That is one problem.
A more serious problem is, after creating the playback loop and playing it back, I then delete the loop (hit the loop symbol to unhighlight it) and place my cursor on (select) any note in the entire score and find that hitting the playback button plays the score back starting from the very beginning of the score, NOT the note I have selected!
This is really annoying and very time consuming.
I was asked to enter this in Github (haven't a clue what Github is intended for?) and eventually managed to log in and create an issue, despite being faced with a screen that resembled the flight control of an advanced jet. Was then told to supply more details; well I'm doing it here.

Score attached - as if that is of any relevance? Next piece 13 further development section work - incomplete.mscz . It happens on all scores I work on in MS 4.0.
I notice other playback issues, for example sometimes the start and end arrows for the playback remain on screen in spurious irrelevant places. But that is secondary.