Multi-Account Containers doesn't save settings if you disable it? Seriously?
I've been having an issue where FF tabs stop letting me detatch or move them. I tried disabling all my extensions to see if that was the issue. Now I'm reading that MAC settings don't get saved if you disable it? What the heck!? No warning, no nothing? For me, this is a must-have feature for FF and it's the reason I recommend it personally and professionally. How is this not saved somewhere or part of my FF profile? I have to now try and remember all my site settings and containers and rebuild all of it. I can't believe this isn't a standard feature in an official extension.
I wasn't aware of that issue. Do you have any recent backups of your Firefox profile folder? (Profiles - Where Firefox stores your bookmarks, passwords and other user data)
I don't have any recent backups but I tested creating new containers, disabling, and reenabling with the same results.
There is a history of this issue as well: