Hi Andreas, lately this happens more and more often, see screenshot, should be self-explanatory. 
To normalize this, you have to change the trigger category.
ah I think this happens if you started creating a key sequence but didn't add any keys, is that possible?
I can't say exactly under what circumstances that happens. But right now I was in "shortcuts" and clicked + to add an action.
edit: No big deal, just wanted to let you know. It might be a bit confusing for beginners 
I think it's just missing a condition for the display filter, will look into it!