OpenAT Keyboard handler suppresses Keyboard Events if ...

Hi Folks

My keyboard routine works well. I subscribe and listen to the events generated by OpenAT.

Now I want to react on 3 keys pressed together. Means I increment my counter on the key pressed event and decrement it when I receive the key up event.

That also works. But only sometimes.
I started to print out those received events to the terminal and noticed that the more I press around on the keyboard, the worse it gets.
First it can handle two keys pressed at the same time, then it starts to ignore the second pressed key, finally OpenAT stops to send any KeyEvents. Even when I release all and only press one at the time.

Did anyone made similar experiences?

Any workarounds?