All you former Technical Preview persons:
Go to your
www.microsoft.com account and check out
Devices. You will probably find multiple entries for the same device serial number, including what version of Windows and Build. Microsoft uses this device list to coordinate your syncing. I have noticed that my login speed has greatly improved after cleaning up this list, by removing devices.
I have two machines running Windows 10 - a Surface Pro 3 and a MacBook via Parallels. Each had multiple entries, to the point that
there were 11 devices on my list. Cut back to the two.