I confirm. When I try to get clips, not all clips are returns.
For example:
curl -H "Authorization: Bearer xxxxxxxxxx" "https://api.twitch.tv/helix/clips?broadcaster_id=22484632&first=100&started_at=2020-01-23T00:00:00Z&ended_at=2020-01-24T00:00:00Z&after=eyJiIjpudWxsLCJhIjp7IkN1cnNvciI6Ik1UQXcifX0"
100 clips are specified, but returns about 40. 60% is missing!
The problem with clips API lasts for many months.