Maya 2017 blendshapes with diven keys, stop working while animating even crashing
 

Hello.
I have a character whose face is animated with control shapes translations as driver for driven keys for the blendshape node. So nothing fancy and I rigged the character by myself. The character is loaded as reference in the anim scene. If I start animating, everything is normal. But after some time, lets say 5 minutes, I realize that the control shapes dont drive the Blendshapes any more. I check the sliders on the blendshape node and they move but the mesh does not deform any more. So I just reload the characters reference and it works again for some time until it happens again. ( Its always the same BS which stop working) But now it got even worse. If I move certain control shapes Maya freezes and stops working. The nodes I have on the characters mesh are from top to bottom: model:renderGeo (thats how I named the mesh), model:skincluster99 , model:faceBS (here are my BS) and last is model:tweak131. So thats really annoying whats going on here. If I open the scene in Maya2016 : same result. Any help is highly appreciated.