Why does the Unity HingeJoint2D not work when enabled during play?

I have two HingeJoint2D, and I fill one 'Connected Rigid Body' field with the other collider. If I hit play, it works just fine. But, if I deactivate the two GameObjects, and then hit play, then select both of them and activate them simultaneously, the hinge stays put and rotates around its anchor, but the connected object is not constrained to the joint. It drops as if it were not connected in the first place.

I'm confused as to why this behavior exists, because I am pooling HingeJoint2Ds and cannot use them properly when they are reactivated.