YouTube ContentID API Empty List of contentOwners

I have access to ContentOwner account and Brand account that are connected.

I'm trying to fetch list of contentOwners for the Brand account. I perform this requesthttps://developers.google.com/youtube/partner/docs/v1/contentOwners/list?apix_params=%7B%22fetchMine%22%3Atrue%7D

and results is 200

{"kind": "youtubePartner#contentOwnerList"}

Why I'm not getting any results? This YouTube channel has monetization enabled. I'm able to log in to the ContentManager account as an administrator.