Contact Relationship Report fatal error if used from the API with a relationship_type_id filter (also affects excel export)

I wanted to use the "Relationship Report" (contact/relationship) via APIv3, using an instance that filters on a relationship_type_id (i.e. lists all relationships of a specific type), but had a fatal error:

[nativecode=1054 ** Unknown column '11_b_a' in 'where clause']

$ drush cvapi -u 1 ReportTemplate.getrows instance_id=50
Array(
    [error_code] => no such field                                                                               
    [sql] => SELECT contact_civireport.sort_name as civicrm_contact_sort_name_a, contact_civireport.id as civicrm_contact_id, contact_b_civireport.sort_name as civicrm_contact_b_sort_name_b, contact_b_civire
port.id as civicrm_contact_b_id, relationship_type_civireport.label_a_b as civicrm_relationship_type_label_a_b
      FROM civicrm_relationship relationship_civireport
     INNER JOIN civicrm_contact contact_civireport ON ( relationship_civireport.contact_id_a =  contact_civireport.id )
     INNER JOIN civicrm_contact contact_b_civireport ON ( relationship_civireport.contact_id_b = contact_b_civireport.id)                            
     INNER JOIN civicrm_relationship_type_en_US relationship_type_civireport ON ( relationship_civireport.relationship_type_id  = relationship_type_civireport.id  )
    WHERE ( ( contact_civireport.contact_type IN ( 'Organization') ) )
           AND ( contact_b_civireport.sort_name LIKE '%Example Org%' ) AND ( ( contact_b_civireport.contact_type IN ( 'Organization') ) )
            AND ( relationship_civireport.is_active = 1 )
            AND ( relationship_civireport.relationship_type_id IN (11_b_a) )  GROUP BY relati
onship_civireport.id
             ORDER BY contact_civireport.sort_name ASC, contact_b_civireport.sort_name ASC  LIMIT 25 [nativecode=1054 ** Unknown column '11_b_a' in 'where clause']

This also affects reports being exported to XLSX using the civiexcelexport extension (which currently calls "beginPostProcess"  and "buildQuery" directly, but I will change to using the API if possible, and if not to beginCommonPostProcess().