Animation loses collision

I have a premade game file here

and when I add another object to the scene, it has collision in game mode, the spider bumps into it and walks on top of it. BUT, when I animate it with an “always” sensor and “action” actuator, all of a sudden all the collision stops. How can I fix this?

None of these things have any collision sensors or collision physics how is it even possible for them to bump into each other?