Custom Node interprets MaterialAttributes inputs as float3

It seems that the Material Editor's Custom nodes don't handle inputs of type FMaterialAttributes correctly, and instead interpret them as float3.

Using Material Attributes as an input to a Custom Expression causes the HLSL Translator to create multiple CustomExpression# functions, for each used member of the Material Attributes, rather than using FMaterialAttributes.

1. Create a material like this, where a MaterialAttributes struct is used as the input to a Custom node:
   [Image Removed]
2. Observe shader compilation errors and/or generated HLSL code indicating that the MaterialAttributes input is interpreted as being of type float3