Sort in a relation form field widget

I am having an issue getting a relation field in the back end to sort by name. The relation field (a belongs to many) only seems to sort the checkbox options by the sort_order field. My model field has the following:

amenities:
            label: Amenities
            nameFrom: name
            descriptionFrom: description
            span: full
            type: relation
            defaultSort:
                column: name
                direction: asc            
            tab: Amenities

What am I missing? Thanks in advance for the help.