MS4 note entry sometimes starts at wrong point

I am finding that the 'insertion point' is often not where the highlighted entry note is. I have lost count of the times I have thought I was inserting at one point only to find that the keystrokes were replacing the wrong bit of the score.
I haven't managed to document a repeatable procedure to make it go wrong but it seems to be happening a lot. Perhaps there is something I am missing which would make it more obvious where the notes will get inserted?

I'll see if I can make it more reproducible.