I have a player (sphere) and 4 enemies (capsules). All enemies have a character controller added. They also all have a child GameObject, which has a RigidBody (no mass, no gravity) and a Box Collider attached. The Box Collider is large enough so you can see the sphere model inside of the box, even with a little space in between.
The player also has a character controller, but no RigidBody. It does have a sphere attached with a mesh collider.
All of the enemies have the IsTrigger box checked. Why don’t they call the OnTriggerEnter() function? What am I missing? Note that when enemies collide, OnTriggerEnter() is called. But it doesn’t work on the player.