This happens in Mint 20 in a VB VM, and also on a raspberry Pi.
If I have no printer set up, then I can run my app and choose Page Setup or try to print (i.e., execute HTMLViewer.Print) and the appropriate dialogues come up and can be examined. Not much can be done without a printer, of course.
So I have the OS detect our ethernet-connected printer, and I make it default printer. I can then print a page from such as Firefox and it works.
However: if I start up my app, or run it with remote-debugging, and do even so much as select Page Setup, the app crashes. Terminates and vanishes immediately. Same thing if I try to print.
Are there any known issues in this department? I couldn’t see anything in Feedback.