Operating system: Windows 10
Graphics card: GTX960
Broken: 2.83.6, 2.90
Short description of error
Rendering mov/mkv/mp4 at 24fps on 2s - The render makes files that report as being 12 fps .
When imported back into Blender the mkv plays back at it's reported frame rate, but the mov and mp4 play frame for frame (2x speed).
Exact steps for others to reproduce the error
Render mov, mkv and mp4 using step = 2, import the results back into Blender. The resulting playback speed is different. Mov and mp4 don't play back on 2's.