”First we tried to convert the h.264 using a different codec, but it wouldn’t work in any converter, so we had to request an uncompressed version of the h.264 file and then we converted that to have the same codec and framerate as the other files. ”
What converter did you try then?
H264 to ProRes conversion works in:
Mpeg Streamclip
Compressor
FCP Log and transfer ( with canon FCP plugin and the THM metadata files)