No export for sessions though it says you can export. The most telling is there is no importing of sessions anyways. Backup does not work. I gave the full file path to the back up folder then restarted the browser and found nothing. Exporting your settings is the only one that works. The ability is to sync doesn't seem there either. "Sync auto save sessions" being checked by default doesn't seem to sync anything. "Enable Cloud Sync" is appended with "(Beta)". So there doesn't seem to be a way to reliably store your sessions to use them between devices using Firefox. Google Drive stores general files so I don't understand how Google Drive can be used to sync sessions between devices and browsers running the same extension. I use Firefox Nightly. There is also no way to simply add a tab to a session which may be on another window. You must copy and paste the URL to the window you want, then rewrite the session to group that tab with the ones you want. Overall, it is good, but unless if you are only using one browser on one device, the ability to backup, export, and sync really lowers the score for me.

Since some weeks ago, it's not saving on browser exit. Still a good manager.

Cloud sync is useless. Neither saves sessions to Google Drive nor syncs with other computers.