I have recently done a massive upgrade on my edit system. Replaced my CPU and updated all my edit software. From MC 7.8 to MC2018 (8.10?) Windows 7 pro to Windows 10 pro. AAE, AME and Photoshop updates as well. I installed QT per AVID new custom specifications (since the breakup).
My workflow has always been to do mixdowns on my sequence and output a QT reference to AME. I used to use Squeeze, but am happier with the h264 compressions and speed of compression in AME. Anyway, I exported a QT reference to AME and the audio showed up but the video was simply black. When I re imported the file into MC it showed up.
I contacted AVID, but really didn't get any good answer except to contact Adobe. That hasn't proven so fruitful either. Anyone else have this issue? I'm working around by exporting out a DNxHD, but it's so much more time consuming.