Opening Illustrator 2019, I see the intro page with my recent work. I click to open it, and it seems to "think" the document is open - I can see my un-embedded layers panel full - but the intro page won't disappear. I can't close it, the arrow next to the AI icon won't collapse it, and I can't work without quitting the app and trying to reopen again. Does the same thing whether I open from the Finder or from the Intro page. MacPro 2012 (5,1) upgraded CPU and GPU (NVIDIA GeForce GTX 980 - flashed). I realize it's not a "supported" GPU, but it's worked on everything else. Still on MacOS 10.12.6 Sierra.