I have recently set up a "new" iMac (2019, 27" 5K, 72GB RAM, Mojave 10.14.6). Most of my Adobe apps seem to be working fine. But (because of issues with my vision), I have tried running the screen at lower-than-5K resolution (4096 x 2304). In the lower rez, everything looks great (and larger), BUT, when I open an image in Photoshop, its title shows in the header tab, and its thumnail shows in the Layers palette, but the image itself is completely invisible! The only solution seems to be quitting P-shop, resetting the rez back up to 5K, relaunching P-shop, and then the image becaomes visibe (and editable). What gives? Is P-shop simply non-functional when running at 4K?