TL;DR: Make sure you're on the latest... turn Sync off on the computer that isn't showing the remote tabs, then turn Sync back on. Details: Three computers (Windows), a phone, and a tablet. Firefox 124.0.1. Sync is enabled and generally seems to be working fine. But I just noticed, on one computer, that when I went to Firefox View, and clicked on "Tabs from Other Devices", that it was showing nothing, other than the, "Log into your Firefox Profile", which I was already logged in... so that was messed up. Did a number of things, like checking the other computer, manually syncing from the other computer, coming back to this one, and telling it to manually sync. It also seemed to be stuck in syncing (a grayed button that said "Syncing...") I looked, and there was an update available to 124.0.2, so I used this opportunity to upgrade. When I came back in, I still didn't have the remote tabs showing up, so I turned off "Sync" entirely, but didn't log out of my Firefox account, and then turned it back on. Now I'm seeing the remote tabs. That's how I fixed it. I hope it helps. I see others having Sync problems, and getting terrible suggestions that are not helpful. In this case it's the simple thing that fixed it for me. Turn it off and turn it on again. If that doesn't work, unplug the computer from the wall and plug it into another outlet. ;-) ( That's a joke for those of you with a sense of humor. )