Unable to set a manager when doing a Refine Result on a report.

Unable to set a manager when doing a Refine Result on a report.

I have created and scheduled a "Soon-to-expire User Account" report. But when I try to use the Manager Attribute as a filter on the report I'm not getting any list to select a name.
I have created a custom Attribute called Resource Manager and here I'm able to write the Names that I want, but I also want to be able to select a Manager.

When I click the small pen I only get a blue baner called "Set a manager" and nothing else. (And the box where the names are to be shown (Beside the small pen.) is grayed out, feels like the field is locked.)

Do I have to do some kind of configuration to get this working?
                New to ADManager Plus?

                  New to ADSelfService Plus?