It looks the same for me too on Windows 10, Dorico 3.1. For those of you having the issue, what printer do you have selected in Print/Printer (not Graphics)? Maybe I’m wrong, but I thought I remembered that Dorico is actually using the printer driver to generate the print preview, which is why sometimes the page size can appear wrong on screen, but will export ok. If you switch your printer to Adobe PDF or something, does the resolution change?
I have a 40" 4K monitor with 3840x2160 resolution scaled to 125% so I can read e-mail and screen icons. I suspect this combination affects the Print preview resolution, since if I do not compensate for the native 3840x2160 resolution (and tiny Desktop icons) the Print preview is clear.
I am still investigating ways to set just Dorico to native resolution if it is possible.
Super update, I have only 1 problem. I don’t know if it is a known issue already but the preview in print mode 3.1 is not sharp on my system. When I print it to PDf or a printer it is ok. So the problem is not so big but ik looks so cheap suddenly. Maybe it has to do with the different view of Dorico. Everything is bigger now (waht I like). My screen is set to 125% Windows 10 (do I have to change that?). The other modes look sharp.
An update on this issue: James has looked into it, and it’s a bug in Qt, which we will fix. We have no plans for another update imminently, but whenever that update comes, it will have a fix for this problem.