I upgraded to 12.4, I had been using Universal Control between two MacBook Pros (Intel ones that are still new enough to support Universal Control) and it had been working great. But after upgrading to 12.4 Universal Control is not working any more.
I read a bit about how to try to fix this in other forums. It seems like the thing to do is to turn it off (uncheck the 3 boxes in the Display Preferences) restart the computer(s) and then turn Universal Control back on again.
That changed the checkboxes but didn’t allow the mouse pointer to cross systems.
There's also another strange symptom. On one of the laptops the third check box (the one about automatically reconnecting) won't check. I can't click on it at all. It does not look "disabled" (greyed out) but it won't check. I suspect that laptop is the one with the "issue" and the other one is probably working fine (it takes 2 to tango though).
One more odd thing. Both Macs have external monitors hooked up. On the Mac that was acting strange I unplugged it from it's Thunderbolt hub (how it is connected to the monitors) and now I could check the third box. Universal Control still didn't work though.
Oh yeah, for what it's worth I tried turning Universal Control off on both Macs (and restarting both of them) too.
I say that because most of the stuff you read about "Universal Control" is about connecting a Mac to an iPad. But clearly it's supposed to support 2 Macs.
Since this is a new feature on a new release are people finding a need to take cleanup steps or have solved this yet?