The fix appears to be to disable a specific display driver policy:
Computer Configuration\ Administrative Templates\ Windows Components\ Remote Desktop Services\ Remote Desktop Session Host\ Remote Session Environment\
set "Use WDDM graphics display driver for Remote Desktop Connections" to disabled
Steps:
- Disable the policy described above
- Restart host computer (one you're remoting into)
- re-connect via remote desktop
- re-arrange desktop windows
- disconnect
- re-connect to test and verify nothing has been compacted back to primary monitor.
Credit to TP [] on the technet forums.
Post this was resolved on: