Provide unique values from a user profile field in a content type field (How to use DISTINCT in ER View)? My users profiles contain a field with department name.

How can I make the unique values from department available in a select list within a content type field?
i.e. Sales, Marketing, IT, etc. (to avoid duplicates).

UPDATE:

I created Entity Reference > Select List > User (target type) + a view with ER that contains the user profile field department, but Query settings DISTINCT still doesn't get rid of the duplicates.

I even tried views_distinct module with Filter Repeats.
Try using aggregation. Set this value in your View under Advanced > Use aggregation. The Group Results Together aggregation type should be the default and should provide the behavior you're looking for.

If this isn't quite what you're looking for, please export a copy of your view configuration, from Configuration > Development > Configuration synchonization > Export, then select Single and find your view under the Views dropdown and update your question with this export.