Modal dialogs lose focus when done, but don't close

Hello,

I am using IntalliJ IDEA Ultimate 2018.2.1 on my MacBook Pro 2017 15" running macOS High Sierra 10.13.6. So far it worked fine, but a few versions ago a strange behavior started. For example when merging origin/master into my feature branch causing some conflicts. When done merging the files the dialog stays open, in the background I get the tooltip that the merge was successful, but the merge dialog loses focus. I cannot bring the dialog back to front by clicking on it, I need to use Mission Control and then focus the dialog again. Clicking on buttons is not possible, then it loses focus again, but closing it via the x button of the window works.

Does someone else have this problem? Is there any way to resolve it?

Best regards,
Christian