help you fix your problem Changed the semantics in the vertex input structure to use ATTR* matching what I have in the GenericVertexInputIndices and voila, it works. I had tried changing all my semantics to ATTR* in both the vertex and fragment shader before and gotten a bunch of domain conflict errors, but didn't notice that it didn't complain about the ones in the vertex input structure. Apparently they're only for vertex input. Another small detail that totally screws everything up.
Conflicting operation in read/write semantics vs. object semantics