Generation is unavailable
Inspect the selected spoken language and local speech-model availability. A language choice does not guarantee that its model is ready on this Mac. Follow the availability message before trying to generate.
The result is empty
Play the selected range and confirm audible speech. Check the intended dialogue track, input range, Mute, and Solo. Music-only material or a silent selection cannot provide the expected transcript.
Try a short, clearly spoken section to isolate the problem. Keep the full project while making that diagnosis.
Words or timing are wrong
Review generated captions as a draft. Correct names and specialist terms manually. Check phrase boundaries and word timing against the recording. A different spoken-language setting may be appropriate if the original selection was wrong, but changing it is not a substitute for review.
Captions are absent from the export
Check the selected track and language, track visibility, and burn-in/sidecar setting. A sidecar is separate from the movie and needs to be loaded by the receiving player. It does not automatically appear in every playback application.