Loot probability and number

For example, even if I set scrap to 100%, there's no scrap in the box,
or even if I set the number of loot items to 2-3, there are 4 in the box.
This happens frequently when I set up a new server and only add categories using the default settings, excluding any other plugins that change the route.
Is there a way to resolve this, or is the way routes are established and the number calculated differently from what I understand?
If I want 100% scrap and 2-3 items in the box, how should I set it?

@The_Kiiiing same issue

@The_Kiiiing