I reinstalled the app after it started to show the blank window. Didn't help, the reinstalled app shows only the same blank window. Since then I can't find any Shot Designer folders in the Documents anymore so I can not repeat the first solution. The second one simply doesn't help with this blank window issue.

Doesn't work. The app still appears as a blank white window

Just tried your first solution for Windows. I moved the mentioned folder to my desktop but since then Shot Designer wont start. The window pops up but its just pure white without any buttons or anything. It happened right after i lost my recent project containing several pages due to this saving issue.. very frustrating.. Any ideas or suggestions?