Recently, many longer runs submitted as Twitch highlights have had parts of their audio muted due to Twitch's automatic copyright detection, the most frequent case being long sections of Lost Woods music. Some vods will even give a network error at these parts which can cause several minutes of footage to be unwatchable. Both of these problems are an issue for leaderboard verification as we require all runs to have full video proof with game audio present throughout the entire run.
Because of this, we highly recommend local recording, which can be done simultaneously while streaming, and uploading the local video file to YouTube instead of using Twitch's highlights, which will avoid the aforementioned issues and be generally more reliable than a livestream vod. Using Twitch's "export to YouTube" function does not prevent these issues from occurring since it will use the highlighted video.
If you have submitted a run with either of these issues and do not have a local recording to upload instead, you can try to dispute any copyright claims that appeared on the video, or try double-checking the original broadcast to see if it shares the issues. If it does not, you may be able to download the full stream vod then trim and upload the run from there.
Lastly a little reminder that it's possible to only record specific audio tracks while streaming, such that stream alerts/music/things of that nature will be omitted from the local recording, but still heard on stream. Having clean unobstructed game audio is always preferred for submissions, so this solution is a nice compromise.