Preserve the recording you have
Do not overwrite the sample while investigating it. Identify a moment when the missing sound should be unmistakable. A short application cue is a better reference than a long passage where it is difficult to know whether the expected component is present.
Inspect tracks rather than adding volume
OBS notes that ordinary players play one audio track at a time. A file made with isolated narration and application tracks can therefore sound incomplete when the player selects one stem. Inspect the player’s actual audio-track list and compare each recorded track with the routing note.
This is different from turning up a source that never reached the output. If another track contains the expected sound, preserve that observation. If no recorded track contains it, return to source assignment and enabled output tracks.
Report the actual handover problem
For a reviewer, the right fix may be a complete listening mix in the next recording or delivery copy. For an editor, the isolated source may already be exactly what was requested. Decide according to the recipient rather than assuming that separation is always better.
A useful result names the artifact, selected track and the component heard. This article does not report an inspected OBS recording and does not establish that every missing-audio case is track selection.
Questions answered
Can a file contain sound that I do not hear on its current track?
Yes. A different recorded audio track may contain another component.
What if none of the tracks contains it?
Investigate the capture and recording routing stages instead of treating selection as the explanation.
Sources & further reading
Official references for the subjects discussed. Service terms and device software can change.