According to the [Apex] Clothing Overview section of the documentation:

Colliding with Rigid Bodies

Rigid bodies present in your scene will push clothing around roughly as you might expect.

Well, I beg to differ. The Apex Cloth collides with the floor just fine, but that's about the only thing it collides with (unless I add ragdoll to the same skeleton that the cloth is attached to.)

So for example, if I try to bounce a ball (dynamic rigid body) into the cloth, it simply bounces through it. If I try to walk an actor with ragdoll through it, he simply clips through it as well.

Anyone have any insight on this?