I thought it was odd as well - that a good graphics card like yours was doing that. I had Hubby look at the photos and he mentioned something and he loaded up a game save of his and showed me that in CAS things look different than they do in-game. Specially with custom content patterns.
I've noticed that before, but couldn't figure out what was going on. Now I know.
I'm happy we were able to figure it out!!
Again, Thank you for asking and letting us troubleshoot the problem with you.