Error Compiling Movie h.264 Selector: 9 Error code: 3

I know others have written extensively about this issue too, but the fix that everyone seems to agree on (toggling the GPU acceleration) is not an option for me as I'm on an Apple Silicon MBP (running Monterey) and that option is ghosted out.

The issue persists only in a single production, *and only when exporting with audio* - if I export something prores and then try to convert that to h.264, even in media encoder, it gives me the same error.

A co-editor working on another system (but running big sur, and an intel chip) opened the same production and can export everything h.264 no problem.