I'm not sure whether this is related only to IntelliJ but so far I haven't experience following issue with any other application.
When I use modal dialog, like one for auto generated code. After the code is generated I cannot use keyboard, it doesn't respond inside editor. The mouse however still works.
The workaround is to click somewhere else to lose focus, and the click again on IntelliJ after the keyboard starts working again. It happens every time under described condition.
The system it's running on is Arch Linux with:
- kernel 5.3.1-arch-1-1-ARCH
- Gnome 3.34.0
Let me know if I can provide some additional details in order to diagnose the root cause.