Problem with morph targets. Black surfaces

Hello,
attached image explains it well, but my problem is Im exporting my rigged model from Maya as a fbx, every morph target/blendshape works fine. But when I apply the corrective blendshape on the elbow it shows that black area.
I tried almost every import/export option. I even activated the Force all skinned meshes to recompute tangents but I couldnt get any solution.

Do you know what can I do? Thank you so much in advance!

hello,Have you solved the problem of blackening at the elbow when applying the corrected blending shape。