BTW. Depending on your Kontakt settings, then a Midi CC7 somehow can change volume. But it can't be notes and velocity then, and you said, you had the issue when you played.
But if you have a pedal or any other control on your controller, that send out Midi CC7? If so, then check that control to see if it's okay and be sure you don't change it when playing. But this should affect any application that use midi CC7 and it's the Generel Midi CC for Master volume, so many applications respond to this.