I have two Viewsonic 4k monitors and Mac Pro. It's worked fine for a year.
Today the secondary display on Monitor 2 started arbitrarily jumping to Monitor 1, vanishing the primary display. This annoyance comes and goes rapidly. I can't make heads or tails of it. I can't get any work done.
I trashed Prefs. I fiddled with System Prefs -> Displays. Reboots etc.
Any ideas on what to do next?
May I know which version of Lightroom are you using/?
The most recent. I upgraded to the most recent last week (as it was released?) but the problem persists.
Release 2015.8 Build 1099473