Brink,
This is what I did:
- made a brandnew MS account
- signed in this new MS account with both my laptop and desktop PC
- this new user has all default settings
- Sync settings ON on both...

Correct. Onedrive options/devicebackups just shows a message "No devices are backed up to Onedrive"

Brink,
The "Files" folder on Onedrive just has the standard Pictures, Documents, Music and Public folders...that's all!
The sidebar under "PC's" lists both my computers.

I have both PC's signed in to the same MS account.
Both PC's have all sync settings on!
When I e.g change the theme on one of the PC's it gets changed on the other PC too!
So sync is working, but...

No sync folders in onedrive.com options/devicebackup.
I have 2 PC's both logged in with the same MS account.
Both have the account sync settings ON
I don't have the backup folders like on the...