Black screen at 120fps

XAVC-S high frame rate clips don’t work in the current OS. Many, many threads about this. You either have to convert the files or shoot a different format. XAVC-HS works.

Very frustrating. Is this due to the new final cut update or strictly OS update?

Whats the best way to convert them?

Handbrake seems to be the only application that will convert the media.