I get Inventor files from my biggest customer. One of my biggest problems is losing some surfaces when I import to BobCAD. I always ask for a STEP and an IGES (never had luck with .DWG) and STEP is usually better than the IGES. That's just a general tip to save you some headache when importing Inventor files.
BobCAD's 2D operations (like drilling, profiling, engraving) will not accept geometry from a solid. You must first extract the edge by going to Utilities - Extract Edges - Single/Solid. Then BobCAD will be able to work with that 2D geometry. Did you do this already?
I would suggest when you extract the edge that you create a new layer like SOLID - EDGES so you can easily hide your surface date to select the newly extracted geometry.
I apologize if you already did this and I'm misunderstanding the question. Let me know what you find.
P.S. So you have a VMax? That's a wicked machine!