Sorry to hear you were having trouble. There's not much for me to go on here, but what you're describing sounds like an issue with Firefox itself that affects a small handful of Tab Stash users, where Firefox's extension APIs sometimes don't work.

This can happen due to Firefox's saved session data getting corrupted. Tab Stash naturally uses Firefox's tab/session APIs quite a bit, so when things don't work right, Tab Stash will naturally also stop working.

Please try the steps here to see if it helps: https://github.com/josh-berry/tab-stash/wiki/Restart-Firefox-Without-Saved-Session-Data

If you're still having trouble, please see https://josh-berry.github.io/tab-stash/support.html for some more common steps to try, and feel free to open a GitHub issue if you're not able to resolve the problem.