Congratulations on find dishes and getting things up and running.

Never heard of that receiver but companies have to pay a licensing fee to do AC3 and most of the off the wall boxes don't do that.
Just because it has the symbol built into the OSD doesn't mean it will decode it.
You would have been better off getting another microHD or similar receiver. I'm sure though that the AC3 problem never crossed your mind.
I would ask the seller about it first about AC3....but return it and get a receiver that will decode AC3.