I am having the same problem, and starts in the exact minute every time where theres is o transition or special effect, only Red color treatment, when open the edl I get video for about 20 seconds and then gone, but my problem is with red 4k files, so I do not think is about QT only, if I render the file I get the black starting from the same point and from there I can only see some other files in the time line that are QT, so is not quik time, can it be the relation with QT files and red files, I think that before inserting those QT files everything was fine
TEST; I remove all Qt files form the proyect and still the same
Mario