Animations are not reacting to changed "to" property

We have encountered problems building scalable Animations.

We want an Animation to react to height changes, but if we use the height property of the target element the animation does not get updated. We tried explicitly setting the "to"-Property, tried NumberAnimation on Y instead of YAnimator and tried animating another property and using it for the "y"-property directly. Nothing seems to be result in an update of the animation.

Maybe our use of MultiEffect for masking contributes to the problem. We had to use an Item-Container to get the animation working in combination with the mask. Maybe we are doing something completely wrong, but an animation not changing to an updated property seems to indicate at least one bug to us.

Please see the example in the attachment. It also includes commented out variants which worked/didn't work.