Caldav/cardav won't sync rev 8.xxx

Suddenly with rev 8.x.2951 I can’t get cardav/caldav to sync. I’m using an Apple “app specific password” as they require to sync with iCloud, and it’s been working fine for years, including after my move from rev 7 to rev 8 a month or so ago. Suddenly quit syncing 4-5 days ago. I’ve gone into accounts and re-entered the Apple generated password but no change.

Any ideas?