I just updated my MacBook Pro mid-2012 Retina 15in to the latest OS X and now that I've rebooted it doesn't want to go into dual screen anymore. I've used this setup for a long time now (couple of years) and it's never been a problem. I'm connected with a mini-DP to DP cable, and I've tried to reset the PRAM/NVRAM already.
When I connect the cable to my Mac the MacBooks screen starts flickering a few times, then I get a "No signal from cable" message on my other screen and everything goes back to normal on my MB.
I'm really at a loss as to what could possibly be the reason, are there any logs I could look at to see what might be happening. Any help would be greatly appreciated :)
EDIT: I tried booting into safe mode and back, didn't work either. I'm looking for a HDMI cable but may have to buy one to test if that works.
EDIT2: I managed to find a HDMI cable and it works fine with that but not with the miniDP to DP cable. Weird.