I’ve posted about it including the time it quit for me. I’m like you - iCloud legacy then moved to iCloud new. All without problems.
I decided yesterday to add bonjour. I have an always on Mac at my house - after learning the hard way that my MacBook wasn’t the ideal base station because it won’t sync when asleep, I moved to the always on Mac and set it to take incoming. I’ve since told all my others to talk to that machine and sync the two databases I use amongst them. After initial syncs, so far it’s been nice. Nice enough that I wonder why I didn’t add bonjour long ago.