I am trying to: create a new custom field group (a test field called 'Testagain' ). It says it saves but it doesn't show up in the Post Field Groups page (see screenshot). It also doesn't show up on the post edit page. The new fields do appear in the Post Field Control and the field group is listed as being assigned to them (see screenshot). Why won't it show up properly on the Post Edit page or the Post Field Groups page???
I have already deactivated all the other plugins and changed back to 2015 theme. No difference.
(It also didn't save properly when I added a new field to one of my old field groups - and my old field group no longer appears on the post edit page either even though I didn't change any of the settings about where it should be displayed.)