Intercepting PrtScr in IntelliJ IDEA context menus - how to resolve?

Question

IntelliJ IDEA

Flameshot app.
Screen capture GUI is hung on PrintScreen. Everything works fine, but refuses to be called when any context menu is open. I came across in Idea, but then it turned out that in almost any application (even in the same kate) - the same thing.
You open the File(Edit, Help...) menu and that's it! Printscreen is not responding.
Tell me where you can dig, I really like this tool. Thank you!
Ubuntu 18.10.