I tried and just not having grouped tabs is so painful. That and being embedded in Google's federated system makes it hard to get out. Any advice on how to make the switch in the least painful way?

If you're the only one who has that issue, or it's very uncommon, then it's more likely a software or hardware configuration issue or some corruption on your systems part.

Just saying this, when I used to run windows, weird bugs like that as a cue to do a complete reinstall of windows. Usually would fix every problem I'd been having with every app to date.

Even now deleting everything associated to Firefox and reinstalling the app would probably fix it. The other thing to do is to keep an eye on the behaviour of your browser after installing extensions. Sometimes extensions themselves can cause weird problems.