On Big Sur beta 4 my bookmarks have stopped syncing. I can import a backup and that is fine but any changes give me a sync error. I have tried the normal fixes, even did a complete reinstall.
Safari bookmarks
My bookmarks stopped syncing when I tried to sync after updating to Safari Version 15.2 (16612.3.6.1.8, 16612) (macOS 11.6.2 (20G313). I’m not sure when the last time I tried to sync (a couple of weeks?), but they sure are not syncing now. And I restarted my iMac, etc.
I found a workaround.. for saving Tab Group links:
Open up Tab Groups in the Sidebar on the Left
Control-Click or Right-Click on the name of the Group
Select Copy Links
Paste the links into a Text Only (not Rich Text) document [Save]
What you will see is something like this:
SAMPLE TAB GROUP
Apple https://www.apple.com/
iPhone - Apple https://www.apple.com/iphone/
You won’t be able to restore the Tab Groups if something goes wrong and your groups are lost, but you will have the links. At least if you have a valuable link you can’t afford to lose, you can copy/paste the link to re-visit the page