Hi, do you remember recently being asked if you want to "Refresh Firefox"? This is a prompt shown to you when you upgrade to a new Firefox version (there is a new Firefox version released every month). This feature, confusingly, wipes clean all add-on storage including OneTab's storage. If Firefox ever gets a disk corruption, that could also cause data loss.

I'm very sorry this happened to you. We're working on cloud sync so in the future this can't happen.