Node variable values along a surface boundary

Hello. I'm new to this package and am trying to find my way around. It seems to be great work with lots of capability. Is there an easy way to extract node values from a FieldVariable in a specific region? I have a shared internal surface between two regions, and I want to extract variables at the surface between the two regions. "evaluate_at" with interface coors works for one region, but not the other. If the boundary on one side is a Neumann boundary, is it possible that variable data is not saved on those boundary nodes?

Any help is appreciated.

Thanks, Mark