The last time I tried the Multi Account Containers add-on, it randomly wiped my list of websites after browser restarts and upgrades and there was no way to export the list of websites I had containerized. IIRC, there still isn't a way to do it unless I use Firefox Sync, which I don't.
The addon was also basically abandoned for quite some time with lots of bugs all over the place and was revived only recently. It was an extremely painful experience, to say the least.
I still use the Containerise addon instead because of that unpleasant experience.
That's a shame you've had a bad experience. I've covered many people over to it with most using it extensively with no major issues. I wonder if your issue had been resolved?
