This is more FYI. Tried syncing Safari tab-groups from old MBP to new one and it failed to sync 3 tab groups with all settings being correct.
After looking more into this, I realised I have tab-group named "something&somethingelse". Syncing quietly fails when encountering such character ("&").
To remedy the problem, I opened new tab-group "something" on old MBP and moved all tabs there. Then I removed old tab-group ("something&somethingelse") and things worked.
I think there's 2-3 bugs here:
- do not parse tab-group name
- document characters that can't be used in name until 1) is fixed
- do NEVER fail silently leaving user wondering what went wrong
Hope this helps.