What version of After Effects and what version of Premiere Pro?
Sorry, both are CC.
It doesn't cause a problem for me, and we have not heard of this on the forum as far as I can remember.
Try creating a brand new comp in a brand new project. Add some video and audio. Does that export OK?
I don't mean to be rude, and in no way do I want to be insulting, but I would feel bad if I didn't ask and it turned out to be the problem....
Since that is the symptom if you try to open a Pr project created in Ae using Premiere Pro CS6 - please check that you are opening the correct Premiere Pro. I forget which icon is which now and then and open CC when I meant to open CS6, although I have never made the reverse error. Yet.
Thanks for solving my stupid problem. You were right I had CS6 open. In fact I had never even updated Premiere to CC. lol Now everything works just fine.