Hinge Joint Doesn't Move Unity 2018.4.17f1

I can't get the hinge joint to work, no matter what I do. I have followed several tutorials on YouTube, like this one: https://youtu.be/ti6pKDmQf7w but when I press Play, the object with the Hinge Joint component just sits motionless in the air. It has a Rigidbody with Gravity turned on and Kinematic off. The axis is pointing the right way. It's angled in a way that it should swing on play. But it doesn't move, at all. This has happened through several LTS versions of Unity, so it must be something I'm doing wrong, but what could it be?