Child bone rotation rotates parent bone scaling

I’m using blender to try and rig up a eye mesh, that maintains deformation when rotating, and doesn’t rotate the deformation along with it.

To accomplish this in blender, I create a mesh parented to a bone (rotator) parented to another bone (parent).

In blender, when I scale the parent bone, and then rotate the rotator bone, the mesh keeps the oval shape with the iris rotating across the deformed surface. The deformation itself does not rotate.

However when I import this into Unreal, go into the imported skeleton and try deforming Parent and rotating Rotator, the parent deformation rotates and the parent deformation is not maintained.

Is there something I’m missing? I thought child bones could not affect parent transforms, yet the deformation is being rotated with the child bone!

Here is my .blend with the rig and mesh. Try rotating the Rotator bone while the Parent bone is scaled along one axis.
Here is my exported .fbx

I simply import the above FBX into a fresh UE4 4.14 project and try messing with the bones in the generated Skeleton object.

If anyone knows another solution for creating cartoony deformed eyes that can rotate and maintain deformation, I’ll gladly follow that method instead.

Hello again,

As with your other question I can’t access your dropbox file. Feel free to e-mail me at test@cryonetic.com and I will have a look.