Hey!
Can you tell me where and how your NPCs are spawned? Also, could you provide me one of the NPC models as an rbxmx file so I could check out some properties as I might already know what’s causing it.
Also can you provide the part of your code that runs UpdateMovement()? It’ll help figuring out what’s going on, on your end. Try spawning your NPCs with HumanoidRootPart.Anchored = false.