It is incredible that Mozilla still recommends this addon. It used to work great, but since Firefox 132 it has some major issues. For me, first time it lost all groups when I installed Firefox 132 (31 Oct 2024). However, back then I managed to restore them via the addon’s setting. Then it lost them again on 10 Jan 2025 when I installed Firefox 134.

Now as others have reported, with Firefox 135, it is impossible to restore the groups via the addon’s settings. When you try to restore from a backup file, it simply closes the browser and when you open the browser again the groups are not there.

Do not waste your time with this addon.