Safari: Tab content vanished

[Cavara34]

I had many tabs in a tab group that now all suddenly appear as start pages; the urls gone. They are not recoverable via 'reopen last' and not bookmarked and not in history. Is there any means to get them to reload?

 

[Konigi]

I experience something similar: I cannot see any tab group on my new MacBook. They still appear on other devices, though. Have you found any solution or work-around since then?