I certainly am not close to an sql writer as this post will demonstrate, but the query below should get you pretty close to what you are looking for.     ( I know for example, that when a task is assigned by teams to more than one person, they will all show on this report even after one person has taking ownership.  )

This was far as I needed or cared to wade through the tables for our purposes,  hopefully it might help.  
( we are running forms 10.2 and Avante on the repository side )

~ Andrew

SELECT distinct 
	  INSTANCE.bp_name,
	  USERS.displayname,
	  LicType =(CASE user_type
			when 0 then 'Repository user' 
			when 1 then 'Named user'
			when 2 then 'unknown'
			when 3 then 'Partcipant'
			when 4 then 'Participant'
			ELSE 'Who Knows'
		END),
      BPIA.resume_id
  FROM cf_bp_instance_approvers as BPIA
  join cf_user_snapshot as USSHOT on USSHOT.id = BPIA.user_snapshot_id
  join cf_users as USERS on USERS.user_id = USSHOT.user_id
  join cf_bp_worker_instnc_to_resume as ITR on ITR.resume_id = BPIA.resume_id
  join cf_form_process_mapping as MAP on MAP.form_id = ITR.form_id
  join cf_bp_main_instances as INSTANCE on INSTANCE.process_id = MAP.process_id
  order by bp_name

  ( the resume_id column keeps things distinct though you could filter it out with an outer select )