Why can one quality option have no audio while another works?

Some streams are split differently by source and may expose separate audio/video tracks.

Does this issue happen only on TikTok?

No. It can happen on any platform when source streams are partially unavailable.

A downloaded TikTok video plays silently or has missing audio tracks.

Refresh the URL and fetch formats again before downloading.
Choose a different available resolution if the first file has no sound.
Verify the original TikTok post actually includes audio and is not muted.
Avoid repost URLs and use the canonical TikTok video link.
If needed, download again after clearing browser cache.
Test playback in another media player to rule out local codec issues.
If issue persists, retry after a few minutes in case source streams are still being processed.

Why can one quality option have no audio while another works? Some streams are split differently by source and may expose separate audio/video tracks.
Does this issue happen only on TikTok? No. It can happen on any platform when source streams are partially unavailable.