ART Animation Tools Epic Games - Export Blendshapes Problem


I’ve a strange problem with BS export using the Animation Tool of Epic Games.
I have a body mesh with skeleton and skin exported inside unreal. It’s my default char.
Then, I’ve created some animation in Maya 15 using the Add Character Tool. So, I can save my txt animation file and also the fbx file.
I know that the procedure of fbx export creates a new skeleton hierarchy connected to the rig one.

I put the fbx inside in unreal 4 and I can see the animation.
All skeleton animation is ok. The problem is about my blendshapes animation. I have done a simply test with eyes blink.
I’ve baked also the channel of target of the blendshapes node.
But only the L side of the blink animation works right.

I try to do export by hand. I’ve baked all the skeleton mesh and the channel of target of two blendshapes of eyes blink.
When I put the fbx inside in unreal I can see every two blendshapes works right.
So, I think there is a problem with the epic games export but I don’t understand what can cause this.

Help me please, it’s not normal that on bs works and the other one no. It’s illogical.
Thank you!