Actually, while my player’s capsule is the root, my enemy has two capsules. the root capsule is used for driving the enemy around the level (i.e. it interacts with worldstatic and worlddynamic volumes), though the player can pass through it. The enemy then has a much smaller inner capsule for blocking the player.
This is done because the player’s capsule is rather large so that he can interact with level geometry properly without clipping through it constantly, and if he were to interact directly with the main capsule of the enemy he would be very far away from it. So instead he can pass through the enemy and then collides with a secondary collision shape at its center, letting him get closer without passing through the enemy. That may have been the cause of the conflict, but it still seems strange that there would be such a disconnect between the way certain collision primitives affect player movement.