I’m getting the same issue, exported videos freeze upon playback, in MPC-HC and VLC.
I exported a 720p video using h264_nvenc. When trying to playback in MPC-HC, black screen, no forward motion, playback time not advancing. If I skip ahead in the video about 90 secs, playback kinda starts, except I get video and audio that is out of sync.
VLC starts playback with correct audio, and a random frame display, frozen. Skipping ahead displays another frame frozen.
thx