It’s important that force 10bit when you do it. The default with ffmpeg is 8bit. That could be the issue you are having.
I bet that was it! Once I finished mine through FFmpeg, it looked perfect.
I never work direct with an x264 or x265 because it’s always very sluggish and it’ll often show the wrong frame when scrubbing back and forth. In ProRes every frame is a key frame so the frame displayed is always accurate.
I couldn’t agree more with this statement!