Both AE and PP should be open, as mentioned earlier. This solved my problem. It’s my first time to do cross-app workflow. It’s a bit strange back-n-foth thing — from Premier to AE, then final assembly in Premier. When I tried opening just the AE, it was freezing and crashing, then I found this solution.
NO, It does not play on QTplayer, only on VLC. Anyways, AfterEffects accepted it. I Rendered it as QT-Avid-dnxhd. Sorry, I forgot to mention. I was on a Mac. Thanks!