Here's a bit of AE wisdom that extends back to at least Version Number 3. Maybe earlier. Never, EVER use mp3 audio in AE. Never try to create mp3 audio using AE.
AE behaves erratically with mp3 audio. Sometimes it's fine, sometimes it's a train wreck. It's intermittent. Save yourself a liot of grief and convert those mp3's to aiff or wav.
I get the feeling you won't be surprised by this particular revelation.
Thanks for the response. I see you (or someone) say this about mp3's all the time. What's odd is that I have been working in 2014 with MP3's every day for the last year
and never had an issue. But you seem to be right...I opened 2015 and recreated the steps using .wav instead of .mp3 and everything was fine. Nevertheless...in 2014 I can and do overwrite .mp3 files all the time with no issue. In fact I satrted using mp3's bevause I would occasionally get serious audio glitches when rendering to .wav. Weird.
anyway thanks again,
still not moving to 2015 as there seems to be random redraw problems with the latest update.. WooooHooo