Staff was being hooked up to (Display 3) MiraCast and (Display 2) HDMI displays from a laptop. Total displays = 3.
Display 1 (laptop) was set as extension and 2&3 were set as main display. This was so that 2&3 could mirror each other, and display 2 would behave well - (ViewSonic board touch functionality does not work when secondary)
Anyway, presentation over, ended MiraCast and disconnected HDMI cable- laptop screen goes black. No other peripherals hooked up. Reconnected HDMI cable, laptop returns to extended display as secondary.
Went back through display settings, manually reset laptop to primary display. Duplicate display just for added insurance. Disconnected HDMI - laptop screen goes black again. Reconnect HDMI, screen returns to normal. Laptop still reading as primary in display settings when they are reopened.
Signed out of user account, disconnected HDMI - laptop screen goes black. Plug back in, returns to normal.
Finally, signed into a different account, signed out of other account. Disconnected HDMI, laptop screen stays on.
We were able to do this several times under the same conditions. Each time I had to sign out of the user account, sign into another user account and sign back out to stop the laptop from black-screening on HDMI removal.