Yes, I have seen this behaviour today. In my case, it does not occur until I click the master bus slider and try to change the overall project levels. Then initially, the whole screen becomes unresponsive to the mouse, but will respond to some keyboard commands such as spacebar to play and stop play. I then discovered that if I press ctrl + O (to open a file), the appropriate dialog box opens, and the mouse again responds. If I cancel the “open” command, I then see the behaviour you describe with the master bus fader slider.
At present, my work-around is to keep well clear of clicking the master fader initially, and the problem does not occur. If I need to alter the setting of that fader, I can do it by opening the mixer window, and moving the master fader in there. This alters the fader also in the main window, which retains its new setting without the mouse problem after the mixer window is closed.
I started another thread about this a few hours ago, before I noticed the strange effect you described. I believe it is a bug, but if others are not seeing it, it may involve an interaction with a particular detail of our hardware or other software. But before I try listing every aspect of my hardware or software, I am waiting to see any suggestions from the experts here.