With Monterey (12.7.1) I set the Macbook Pro (LG Full HD) as the main display. Default resolution for the display. The MacBook Pro built-in Liquid Retina XDR Dsplay shows: use as Extend display, default resolution for display. Preset is Apple XDR Display. Refresh Rate: is ProMotion.
Universal Control has all three options checked.
I used to have a similar problem many years ago and it was because I was trying to cross an area that wasn't overlapped by the two displays. I had one display portrait and the other landscape so I had to be careful moving diagonally if I went from the far side of the landscape one to the top of the portrait one.
The Mac depends on you to tell it roughly how the displays are physically arranged. If that setting is different from the actual physical arrangement, the crossing edges for the mouse pointer may not be where you think they should be.
What I was describing is similar to what Servant of Cats posted. Both have to do with the arrangement of the screens in preferences not matching their arrangement in real life. I am also guessing this may be a bigger problem if you are using different resolutions. It's been about 25 years since I last had two displays. :-)
Limnos, thanks for your reply. Both my displays are in landscape mode, so your suggestion does not apply to my situation.
My external display is set as the extended display but I can't move the cursor from the monitor to the main computer display.
