The red frames issue is something that has dogged Adobe for years, and despite claims of having fixed it, it is alive and well in every version of Premiere or After Effects I’ve used. I don’t run into it often, but when I do my usual fix is to convert the media to something else and edit that. It’s inconvenient most times, to say the least. I’ve had it happen to numerous codecs: ProRes, H.264, XDCAM, etc.
I’ve heard it stems from the software filling in missing frames in order to match the correct clip length, but I don’t know how true that is.