I'm wondering if I'm running into a weird caching issue. As Admin, I'm changing the Full Name of a user but it appears not to get updated. However, if I log in as that user the changes seem to be there. Everybody else, anonymous user, the admin user, etc. all see the first/oldest name.
I discovered this was due to the theme slick, which seemed to be broken to me, as the form and input elements were missing multiple values, which didn't get loaded when save was clicked, so no information was sent. I made a child theme to fix it.