I've had a problem similar to a few others, trying to export multiple fbx files based on an attribute that is generated on the PDG work items.

In my "Geometry Import" node, I have copied all geometry attributes from the Primitive class. I can see them when I click on each work item that's generated. But I cannot reference any of these attributes when I type @attribute_name in the Output file parameter in an ROP FBX output node. When the geometry node cooks, it renders the file with a blank name. @pdg_index works but not any other geo attributes. What am I missing?

Are your cook types matching?
If you're pulling in attributes on cook, they are not available when you use on generate.
Cook types either should match, or you can use generate and then cook types one after another, but not the other way around.