I also never managed to get sync properly working. I use Orion RC on my Mac, iPad, and iPhone: I have the same tab groups on all of them (the tab group names somehow got synced, though I had to clean up duplicates many times), but the content of the tab groups is definitely not synced. Bookmarks sync works a bit better in my experience.
What I would really like is a way to completely reset all sync data, set one device as master, and restart the sync from there. So, once the team manages to make it work better, all of us who are stuck with some crust from the past will be able to start fresh.
I have also tried all the troubleshooting steps suggested in various places, but I’m a bit more careful now because every time I do that, I find all tab groups duplicated (or more…), and every copy has « almost » the same content.