Local recording video recovery

I recorded an important ~35-minute Zoom interview on October 20. The recording has complete audio, but the converted MP4 is entirely black.

I still have the ORIGINAL local recording files, including double_click_to_convert_01.zoom (~837 MB), double_click_to_convert_02.zoom, recording.conf, and the resulting MP4/M4A.

I have already tried normal conversion, manual conversion using Zoom's Transcode.app on macOS, a new-meeting conversion workaround, and multiple video players. Transcode consistently creates a 1280×720 H.264 video containing black frames for the entire meeting.

My camera/recording worked correctly in a test Zoom recording immediately before this meeting.

I’ve tried almost every workaround but honestly need to know if there was a glitch or no way of recovering so I can redo this meeting if so.