Whenever I double click a layer to open it in the layer viewer, I lose my comp viewer until I restart AE or scale the comp viewer to a different size. My comp will play back on my client monitors but the image is frozen in the comp viewer, no matter how many more comps I open.
I am on CC2015 on a Mac Pro 2013 with Dual D500s running OS X 10.9.5 and using a Blackmagic Studio Express.
Well, that's an odd one.
Can we see some screenshots of your interface? Like, do you have the layer panel docked with your comp panel?
It's probably a bug, but I want to at least see if we can narrow down what it is so that when you file a bug report, you can give them as much detail as possible; they can't fix what they can't diagnose!
It happens sporadically, not every time, but next time it happens Ill record a video of the screen so its more obvious.