Mouse/cursor malfunction when changing header and footers

In the latest release 3.6.2 I have a problem on my mac where the program stops working completely. This happens when I try to edit the footer and header section under "Styles". A kind of ghost mouse appears as a little rectangle (about the same size as the normal cursor). It kind of floats around. If I try to click on "Cancel" or "Close" or any other menu item the little box jumps to a new position. It also affects the way the mouse works in other non MuseScore applications. After a bit of fiddling I can get to the "Force Quit" in the Mac apple button top left and I can force quit MuseScore. After this the mouse is working okay again.

If I restart Musescore I can do all the other editing things as normal but as soon as I go into Styles, Headers then the problem re-appears. This is not confined to my desk top. My MacBook Air also has the same problem. Note that I did not have this problem until I ran the latest update of MuseScore. So it seems to be a bug in the latest issue.

Anyone else having this problem? Any suggestions how to fix it?=

Thanks