The problem with Commerce ownership changing

The problem with Commerce ownership changing

Hi,

I am changing the ownership of the company and trying to delete the previous user-owner. 

I changed the owner of the company from user Tatiana to user Eugene. Eugene is the owner of the organization. It's OK. I am now trying to remove the user Tatiana. I'm trying to deactivate a user. 
Error: At least one administrator is required in the Commerce app.

I go to the list of applications and on Commerce I see “Owner”. I click Unassign.

Error: You cannot remove the service admin, at least one service admin is required in the app.

I'm trying in DIrectory - Applications - Commerce to use the Change Owner command.
Error Occurred!
I am trying in DIrectory - Admins - Service Admins - Commerce to use the Change command.
Error Occurred!
In DIrectory - Admins I have added a temporary user Bri as Application Admin and specified Specific Applications - Commerce. However, the Commerce application has only one Admin - Tatiana - in the Service Admins section.

Please help to solve the problem with Commerce and user Tatiana.