Until recently Universal control worked great between my MacBook Pro with M1 Pro an my MacBook Air M2, but not anymore. I can still extend/mirror the screens between the two devices, but they don’t show up for universal control so that I can control both devices with the same keyboard and mouse.
I tried turning Universal control on/off, but without succes. Both devices are on the same macOS version and updating to 13.4 didn’t make any difference. I think the issue is with the MacBook Air, because my iPad does show up for Universal control on the MacBook Pro.
Does anyone have an idea how I can solve this?
Have you double checked to make sure all the requirement are still being met? I know it worked before but sometimes things change on their own. 
Sounds slightly patronising (not meant to be) but having experienced this myself, signing out of iCloud on the main machine, rebooting, signing back in and…waiting…worked for me (and I’m not patient!)
For me, Universal Control mostly works, but every so often the magic gremlin takes a little nap and it stops working for a few minutes or hours or a day. Then the magic gremlin decides it’s time to be useful again and then it works flawlessly for a couple weeks until the next gremlin nap.
Yeah, it’s a headache but overall it’s so useful that I keep the faith.
My setup is a M2 MacBook Pro and a 2019 Intel iMac. The iMac is my status board, holding my calendar and my project management system (Amazing Marvin). Almost everything else happens on the laptop. I move between the two computers regularly using UC.
Did “allow Handoff” somehow get turned off? Even if it didn’t, I would try turning it off and then back on for both devices. Maybe that will kick it in the pants & get it going again.
I did try that, but with no succes.
That’s perhaps the only thing I didn’t try, because I’m not happy with downloading everything again.
I recall you can keep a copy and then there’s not much of anything to download again…
Bummer that the Handoff setting didn’t fix it.
You can log out of iCloud and back in without up/downloading everything.
When you sign out of iCloud, your data is still in the cloud. And when you sign out, you are asked if you want to keep a copy of the data. This will keep everything on you computer (I believe it’s moved to a folder with “archive” in the name.)
If you then sign into the same Apple ID on that computer, you should see an option to replace or merge the data. Merging the data means it will compare each file on your computer with what it’s got in the cloud, keeping the newest version. While it’s doing this, the Finder makes it seem like everything is being downloaded again, but what it’s really doing is making the comparison. All of the files marked with the icon for “downloadable” really mean that the merging process hasn’t gotten to them yet, not that they need to be downloaded. It’s confusing and misleading.
Also, this process can take a long time. You still can access everything, but it might take a day for everything to settle down.
There’s one caveat about Keychain — the amazing Glenn Fleishman explains it here:
That’s the problem, a day is too long at the moment and I remember having a problem with keeping a local copy and syncing in the past. For now I’m just waiting and hoping it might work again 
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Its very much hit and miss for me, works 90% of the time. No real clue as to why it stops (a few times a week for short periods).
It always comes back for me, however incant figure put any rhyme or reason to it.
I can’t get Universal control to work and I even tried the iCloud sign out/in. Sometimes it randomly works for a few minutes or an hour and I have no idea why. Hopefully it will get fixed in an update, because I really miss this feature.
