I've got the same issue! I'd like to transfer my bookmarks and passwords at the very least :/. Did the same. Sync, logged in with my opera account, connected both devices... only thing that works now is Flow. But not a great solution to use flow to transfer everything manually... 🙃 help please.
@tiikuri Flow was designed to directly connect a device with Opera for desktops with another device running Opera for Android, that's why.
It was created for users to be able to continue doing on mobile what they started on desktop and vice-versa.