My computer is set not to sleep or lock, but to blank the display after eg 10 mins. I have 2 monitors, which, prior to 16.04, worked as expected - the only noticeable thing was that, for whatever hardware reason, one took an extra moment or two to wake up after the screen blanked, but it worked fine.
After upgrading to 16.04, when waking from display blank, that monitor gets disabled - it wakes to only one monitor active. I have to go to Displays settings and re-enable (and re-position) it. I checked in XFCE Power Manager and this behaviour exists whether I have Handle display power management ticked or not - so far the only way I have found to stop it is to turn off display blanking altogether.
There are no power/sleep/etc settings on the monitor itself. Anything I can to do tell it not to lose/disable this display?