What’s Wrong with my watch history?

I love YouTube, it my life.. don’t get me wrong. But today I noticed that on the home page it shows some of my watch history. But when I went to the library page, it didn’t show some of the videos there! I’m confused. I thought it was because you had a limit on how many videos you can watch later. Please tell me what’s wrong.

Delilahd1 about YouTube - Watch, Upload and Share Videos, v13.11