I'm hoping this is an easy one ... what setting have I missed that would cause the CB Privacy "Users" setting in the plugin that typically is between "Public" and "Private" to go missing? It happened when I was doing a final conversion to CB 2.0 on a test site. (Please see image.)
Found it. "Profile View Access Level" setting in CB Configuration, where I had already done a careful field-by-field check to the production site. I think the technical term for this is "oops". The upgrade to CB 2.0 does surprisingly change a few settings that are sort of important, and I missed that one.