[Carlos Sandoval]

Ha, I just bumped into this problem, 3 years after your post, this MIGHT JUST BE TOO LATE, but anyhow, for future people having this problem of the exported camera from Maya to After Effects:

In Maya, pull up the camera attributes, under Film Back, Fit Resolution Gate, select Vertical. Never use Fill, or you’ll have swimming nulls in AE. I don’t know why it works for me, but it does. It can drive anyone mad.

If this doesn’t solve your problem, good luck.