[John Whitehead]

The footage Red 4K footage transcoded to ProRes 422 HQ at 2K; there is also some 5D footage transcoded to ProRes 422 HQ at 1080p.

So you are mixing two frame sizes in the timeline. Are they also different frame rates (Red @ 24 5D @ 30)?

What would Disk Warrior do? Does it free up space somehow?

The only thing that will free up space is deleting files, but if your files are fragmented that won’t help you much until you completely erase the drives and copy media onto them again freshly (contiguously).

The dropped frames only happen when moving to or from the timeline-native 2K footage to any kind of rendered footage (color corrected, rescaled 5D footage, or subtitles).

How do you have your render options set? You may have them set inefficiently.

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