FWIW I discovered a different solution after toggling Safari off/on in iCloud preferences didn’t work for me.
On my iOS device, I tried to Share one of the problem Tab Groups via the Messages app. This appeared to trigger something b/c my other devices suddenly “saw” the group and began syncing again. Did not even need to send the message - simply starting that action by opening the messages app was enough.
On my iOS device, I tried to Share one of the problem Tab Groups via the Messages app. This appeared to trigger something b/c my other devices suddenly “saw” the group and began syncing again. Did not even need to send the message - simply starting that action by opening the messages app was enough.