Hi, sorry about this. We've been working with Mozilla all morning to resolve this. Mozilla have confirmed it was due to a bug in Firefox (related to extension permissions downgrades).

To fix OneTab, just go to “about:addons” in your Firefox address bar, click the ‘cog’ icon in the top right, and click ‘Check for updates’. This will upgrade you to OneTab v1.39, which fixes the issue.

We are working on automatic data syncing/exporting.