Clicking edit on my Filter Result gadget.
Finding my custom field in the drop down.
Clicking save - but nothing happens, the gadget stays in edit mode.
Removing the custom field and the gadget can save the change and go back to the filter screen.
I seem to be able to add some custom fields but not others, so my question is - should the field be in a specific Field Type in order to be displayed on the Filter Result gadget.