Jumping Piston Rig - Unreal Engine

Hi guys, acutally I have a big problem with my animations exported from Blender. I am not an Animator and/or Rigger, so I already thought this could be a potential problem for my current project, but I hoped the best.
Well, now I imported everything into Unreal and I have some problems.

In Blender it works just fine, but after importing the skeletal mesh and playing the animation in the engine, the pistons flips around.

How my rig works:
The tip of the constrained bone stretches to the tip of the main rotation bone. The two small bones on top are parented to the stretched bone. These are linked to the piston mesh and it works - in Blender.

I already thought in the making, the stretch Constraint Bone could cause some trouble … but I don’t have any idea how to fix it.

I hope you can help me!

No need to answer.
The solution: The Roll with inverted. Now it works :smiley: