Update: I have PM 6, Canon 5D IV and have found the following. When I open a contact sheet in PM for files that have already been converted to DNGs by Lightroom, when I zoom in on them in PM they are very pixelated. BUT when I load a contact sheet directly from the SD card in CR2 format, it's fine. Does PM not support DNGs? Or what is the issue with the preview/zoom when they are DNGs?
I have Win10 64bit and using DNG images