Maps favourites and guides do not sync to Apple Watch

Maps on my Apple Watch (series 5, WatchOS 7.6) shows only 'Search' and 'Location' buttons when opened. That is, 'Favourites' does not appear. My paired iPhone (11 Pro, iOS 14.7) has 5 favourites and 88 other locations that appear in iOS Maps; these also appear on my Mac (Big Sur) Maps app, and changes on the iPhone or Mac sync OK. My contacts appear on the Watch Maps app under the 'Search' button, and navigation to a contacts address works OK. So that part of Maps is sync'ing OK, but not the favourite locations including Home and Work.

Apart from the two buttons, the text on the Watch Maps app says "Add your home and work addresses using your iPhone to see estimated travel times." But I've already done that... I even changed my Work address (my Card in Contacts) but that did not force a sync.

I've tried restarting both devices. Since everything else seems to synch from iPhone to & from the Watch OK (e.g. podcasts, contacts) I'm reluctant to reset the Watch and setup again...

Any ideas welcome, or is this a bug in Apple Watch Maps?