Restarted my PC and on boot found all my containers deleted. Bookmarks are fine. Browser settings are fine. Other Extensions and Addons are fine. Tabs from the last session were stll there. Everything else is all good. FireFox Multi-Account Containers is the only thing that's gone wrong. Looking at my containers.json (my best guess on what to check) they're all back to default. There's no "Old Firefox Data" folder on the desktop. This happens ~3 times a year usually after an update or if there's a sudden shutdown due to power loss. I've used FireFox Sync before and rather than helping, it ruined everything for no apparent reason. It duplicated the current containers, restored and duplicated old deleted containers and sites stopped using their designated containers. It sucks. It really really sucks. Is there a way to make local backups of containers and their designations? Just knowing exactly what to backup would be a massive help and make this a lot less distressing.