Musescore4 : "frozen mixer popup window", even after restart

Hello,

I am using a windows 10 (22H2) on a Dell Latitude laptop which has a display with a 1920 X 1080 resolution;
I have recently upgraded Musescore to the last version of Musescore4.

In the middle of editing a score , I chose to open the mixer; the mixer popup window opened, but it igot stuck to the top of my screen, and ... I do not have any control , either to close or move that popup window.

Even if Musescore appears still OK with every other aspect, i.e. the visible menus are still active and clickable, and the score is editable (but only for the parts that are not masked by the popup); I am nevertheless completely stuck:

it is impossible to properly edit the score anymore, nor have access to the menus hidden by the popup window, (and it is impossible to close that mixer popup window.
Moreover, If I restart Musescore, and choose to edit a new score... the new score appears, but the "stuck mixer popup window" is still there !

So it is now impossible for me to work with MuseScore

Help !