Find the stream at the source
If an owned export lacks a required track, first confirm that the chosen input actually contains it. Record its stream index, role and format. Another similarly named source file may have a different inventory, so preserve the source identity rather than relying on the filename alone.
Next inspect what the processing job selected. FFmpeg supports explicit mapping; automatic selection is not a general promise to retain every input stream. Streamcopy describes how selected encoded streams are handled, not an assurance that every available stream is selected.
Keep the planned output list beside the input list. A track intentionally omitted for one delivery can later look like unexplained loss if the selection contract is absent.
Separate selection from support
In an imagined package, a caption track exists in the input but was never selected for output. That calls for correcting selection if the destination supports it. If it was selected and the output format rejects it, the next question concerns supported packaging or conversion.
Do not keep re-encoding video to address an unselected text track. Choose the smallest change that serves the required deliverable, writing to a new output. Preserve the original and the exact processing messages.
Inspect the resulting inventory, then select the track in the intended destination and review text or sound. A stream appearing in a probe report is only one acceptance step. The completed handoff demonstrates that the required content survived in a usable delivery form.
Questions answered
Does copying the video stream copy all subtitles automatically?
No. Verify the actual selected output streams.
Is every missing track a codec incompatibility?
No. Establish whether it was present and selected before investigating support.
Sources & further reading
Official references for the subjects discussed. Service terms and device software can change.