Traktor Pro 2.6 issue with Cue button functionality (VCI-400 DJTT)

Hi,

i have a strange issue and can't analyze why it happens.
Sometimes in a Deck (A,B,C or D) the Cue Button(s) stops working. I use the actual "DJ TechTools VCI-400SE Mapping" for Traktor Pro 2.6.
I can't set any Cue-Points in this Deck and the Song will not play when i press the Cue Button. I managed it after some time to work again without disconnecting the controller, but i don't know how.

Maybe it's a functionality i activate by accident...

Does anybody else have this effect and knows why it happens.

Regards
Kabbi