Problems with QuickTime on Windows and 32-bit limitations (answer)
I rendered out a bunch of raw footage into ProRes HQ, UltraHD. On my Surfact Pro 3, 8 GB ram 512GB disk I tried to load the footage into HitFilm.
The first few clips imported and played back, no problem. So I added more. Even though all of the clips are the same format, at some point HitFilm stops loading them, stops playing any of them back (even ones that played back fine when I first loaded them), and when I right clicked and selected "reload" it switched to "File Not Supported" even though clearly the files ARE supported... because they're all the same format
The project files are here:
As indicated, this is a showstopper bug. I'm going to try this also on my mac... hoepfully I'll have better luck there, or else I'll have to go back to Premiere.