Ae file renders as a single frame still, no video

When I add an After Effects (Ae) file to the Media Encoder, hit the green start arrow, it renders super fast and instead of a video (15 sec mp4) being the final, it's a still... .mp4 but 00.00.00 still frame is the output?  No video?  I tried saving a copy with a different name, same issue.  Ae is open and the 15 seconds plays fine throughout in Ae