Why does pitch rotation from controllers not work?

Hello everybody,

I am trying to set up a simple flying movement (pitch and yaw movement) using the motion controllers from htc vive.
The movement of the camera should be according to the movement of my controllers. So when i press the trigger of the left controller the player should move according to the controllers movement.
The yaw movement works fine but I have problems with the pitch movement.

When I try to access the pitch rotation from the controller, the camera should vary its height according to the pitch movement. Now it is varying its height according to the roll movement of my controller, although I only use the pitch rotation.

Does anybody know how to fix this?

Here is the blueprint of the pitch movement

I figured it out!
For some reason it works when I get the X (Roll) rotator value in combination with the up vector.
I have no idea why it is working with the Roll rotator and not with the pitch rotator… I guess it is a bug??