Yeah, I hear ya on that tech assistance...........
Ok, I checked out Nuendo without the Mona turned on and it recognizes my soundblaster. Then when I turned Mona on and started Nuendo again, it recognizes all inputs. SO...............I don't think it's Neuendo. It doesn't make sense that it would recognize just two inputs if all inputs were working. Try recording with all inputs in Cubase. Check your layla console software and make sure all inputs are functional.
You could also try recording using inputs 3-? in Nuendo just to see what happens. And when doing that open the Layla console and see if you are getting input levels. A weird thing about Mona, I'll be recording and only getting sound out of one speaker, so I opened the software console and had to select and deselect solo before the sound would come out of right and left speakers! What's up with that??