Been digging into this issue: User Profile sometimes appears empty. I've had it occur on a client's 5.1 deployment and have confirmed it both in 5.1 and 5.1.2, and I'm a little surprised not to see other people with the issue as I can replicate it easily.
plone.app.users.browser.account.AccountPanelForm.member is returning the expected MemberData object when given a userid.
plone.app.users.browser.account.AccountPanelSchemaAdapter is also setting itself to the MemberData for self.context
However the widgets in the form have no value. If I track back to updateWidgets in z3c.form.BaseForm, AccountPanelSchemaAdapter is executed with the self.widgets.update() call. If the widgets return empty, plone.app.users.browser.account.AccountPanelSchemaAdapter._getProperty is not called (though the context is the proper MemberData obj).
I'm not sure what determines when _getProperty is called. Any suggestions?