BoundaryFromVolumeCF

Dear NGSolve developers,

I recently came across this post: Functionality of the normal vectors unclear? - Kunena
Now, I wanted to implement this in a 2D setting to evaluate the normal component of a CoefficientFunction along an interface (locally, I don’t want to integrate).
However, I always got a normal vector being 0 everywhere. In the 3D case this does not happen and I get nice normal vectors along my interface.
Attached there is a small script showing this behaviour.
Could you please help me with this problem or tell me if I missed anything?

Thank you very much!

Best regards,
Julius

Attachment: 2d_example.py