I have a Surface Pro 4 running Windows 10 Pro.
I have the new Surface Dock for it as well.
In the dock, I have 2 external monitors plugged in.
Last night (1/18/2016) I updated WIn10 to the latest version through Windows Upgrade (included a firmware update, and pretty large Win10 update, along with several Office updates).
Ever since the update, when I lock the screen (Win+L key), and then unlock the screen - the only monitor that still works is the one on the actual Surface Pro 4. The two monitors attached to the dock are gone.
To get them back, I have been just disconnecting the dock connector, and then reconnecting it.
This works, but then all my windows are re-organized and re-sized - which is freakin' annoying!
Has anyone got a suggestion? Is there anyone at Microsoft aware of this issue? Help!