Ion-scroll not working when scrolling up

I have a problem with the ion-scroll directive. In my ion-scroll I have several div items I want to be scrollable.
Scrolling downwards works perfectly, but scrolling upwards does not. I simply can not scroll up.
Scrolling upwards works, when I first scroll down and then change the direction while still touching the screen.

I used the following code for it:

<ion-scroll style="height: 50vh">
            <div ng-repeat="x in xx">

I also tried to add locking=“false”, but this had no effect.
The problem accurs for Android on both device (4.4) and emulator (6.0). I could not test ist for iOS so far.

I have installed latest Crosswalk version.

Any ideas on this?
Thanks for your help