The Recently Added hubs are based on the library, sorted by Date added – most client will limit the default hub to a certain amount of entries… clicking on the hub header will show the full library sorted accordingly.
This is different from Continue Playing.
What you’re looking for is a way to reflect file updates in the Date added property… there’s an existing feature suggestion asking for this.
The same goes for manually removing items from Recently Added
I suggest you comment/vote in those existing threads in order to avoid distracting/dispersing votes (and attention).