Deleted all of my saved tabs after using for a few months. Restore previous session option is enabled and had not issues until everything was gone one day. No way to backup or restore that I could find.

I have about 760 tabs in my session. I worked for an hour and a half with this add-on to set up my groups, and when I reopened FireFox, it had erased all of my work. This add-on thrashed my tabs, then refused to show the management screen. I could see it blink on, then disappear. Sadly, this add-on doesn't work with large tab sets. Good thing I backed up.
[edit] Yes, session restore is enabled. Always has been. How else could you amass that many tabs?

The recent update causes an issue with new tabs - have to retype what I am trying to do twice in order for it to do what I want (do a goolge search, or go to the website)

Did not actually save any tabs, groups kept being empty... only regained my tabs by uninstalling.

I really wanted to love this addon but it's just too stressful to use. As so many others here have already posted, the addon's default behavior of deleting the tabs I've saved into a group is completely at odds with what the addon seems to have been designed to do: group your tabs for opening whenever you want. What's the point of spending the time to create several groups and set them up complete with containers and color-coding if the tabs are just going to disappear? Such a headache. Immediately removed, going back to OneTab.

Worst tab manager ever. Always crash and remove all my saved tabs.

Can't give this any better rating as the add-on is not intuitive at all. I thought that the purpose is to open several tabs, save those tabs into a group and then reopen them again later. Problem is that as soon as you close the individual tabs they disappear from the group. What good is this add-on if the groups don't keep their list of tabs to reopen them later? There needs to be a tutorial that explains how this is supposed to work.

Deletes all of your tabs on startup or orphans them at the bottom.

Despite setting the browser to "start where I left off" my half dozen tab groups are empty undoing all sorting I've spent so much time doing.

It says "it's corrupt"

I searched for it and was happy using it - until it repeadetly erased all saved tabs after some weeks of using it without problems. 2 times. Which makes my work life really crappy.

Lost tabs of days of work
Backup doesn't work as all groups I saved are empty !
What's the f*** with your extension why it hide the tabs !
So after firefox restart all are lost without any reason !

Thanks to this half assed extension I just lost over 100 tabs I had opened in my browser. Thank you.

I just installed it yesterday and so far it f*ck*d everything up it could.

1. I moved some tabs into a new window to convert it into a tab-group but I didn't find any option that offered specifically that. So I choose "Create new group" in the hopes it would do that OR open a new window where I could move said tabs afterwards. It emptied out the current window without asking for confirmation or even a warning instead. :-(

2. Needed to restart my PC so I "closed all [Firefox] windows on this screen" (or however this option is called in English Windows). I expected Firefox to restore both windows after I started it again. Instead it just opened the new little group from 1. and an empty group. My (ungrouped?) window with ~200 tabs was nowhere to be found. :-(

Luckily it seems I was able to restore most tabs that had vanished in both cases.

新版本工具列圖示點擊竟然改成展開群組。
關閉分頁後其他分頁亂跳，切換群組不順暢，毫無長進。

trying to export all my groups from sync tab groups hangs up firefox
it seems like it tries to open all tab in all groups which is just crazy and brings down firefox to crawl which is duh it's like over 2 thousand tabs sync tab groups must work in other way because I never had problem importing that many groups and tabs

and my system is not weak Ryzen 7 3700X and 16GB of RAM with Firefox running on ssd

Didn't work.