Using Remote Desktop & Windows 10 Preview:
Test machines involved
One with Windows 10 and the other has Windows 8.1 Pro.
How Remote Desktop (RDT) works, depends on how one logs on to each machine.
There are two different ways to logon to Windows 8.1 and 10.
You can logon using a local account no Microsoft email involved or you can logon using the Microsoft email account.
As long as the logon is the same way on each machine the RDT connection from Windows 10 works,
However if the logon is different for each system the RDT connection fails, you get the logon credentials screen but cannot get the logon credentials to work.
This problem is only for Windows 10 to 8/8.1. A connection to Windows 7 or a server seems to always work.

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