Why do my NPCs walk around collision groups that are set to false?

I've made my NPCs have their own collision group along with a piece of my map. I'm attempting to make the NPCs walk through the wall (using pathfinding) but not the players. I've gone as far as making the part client-sided only but the NPC still appears to be there on the client's end. Any methods or code to make it so that NPCs will freely walk through something using pathfinding that players can't?