Edit: I fixed it. I found one of Okay Samurai's videos where he addressed this specific issue. My "Head" was "+Head" making it independent of the body. I'm still not sure why the body could not be pinned down, but that's a question for another time. I've left the original text below in case this problem shows up for anyone else.
The two sample characters Anime Rin and Wizard Heather are torsos with hair behind the shoulders. I'd like to do the same with my character, Nick. I'm not sure if that's important or not, but it seems that the Neck element has to be part of the Head element.
YouTube videos are a great help for much of this, but I just cannot seem to get this one simple function to work.
Yes, I'm a noob. This is my first puppet. I removed most of what I didn't need to keep this one problem isolated.
The head, neck, and body float when I make the AI layer a part of the Head group: