Custom Field filter on User record

Question

Is there a way to add a User Filter on the User record based off of a custom field? I assumed that since you can access a custom field using the user() function that it would be possible to access these fields in the same way from a recordFilterList but when I try the below I get an error: "The field [customField3] does not exist". Is there any way to do this either through a!recordFilterList or using an expression rule? 
 a!recordFilterList( name: "OFFICE", options: { a!recordFilterListOption( id: 1, name: "OBI", filter: a!queryFilter( field: "customField3", operator: "includes", value: "OBI", ) ) } )

Chris · Answer

Unfortunately the custom fields are not available in the OOTB User record type currently, which prevents us from being able to add them to filters. If you Edit List within the User record in /design you can see which fields are available by clearing the Sort Field and reviewing the dropdown (basic fields only). 
 Note we can call the user() function for custom fields in the List View to display custom fields, but we cannot use them in User Filters unfortunately. 
 This has my vote for a product enhancement however!