Humanoid changing the cancollide property on some of the parts in the model

Help and Feedback Art Design Support
1

I made sure that all of the parts besides the humanoidrootpart are set cancollide to true, but whenever i play some of the parts have cancollide to off and i cant change it while the game is running. whenever i get rid of the humanoid this doesnt happen. Here is the model:
https://www.roblox.com/library/9895384873/NuclearBoss

it makes it slide around on the ground like this
image

3

In my mind only humanoid root part should have collision, because it is used for pathfinding. Setting other parts of r15 for example to collide would make npc get stuck on corners.

4

But then it will fall becuase the other parts arent anchored

5

Does anybody know why this isnt working