My app in Oracle APEX is a part of the bigger project made in a few frameworks. By years, users and all of they properties was set on another application in Oracle Forms. When I was using Oracle APEX 4, everything was working, but now I have to migrate to 18.2.0.00.12 and here is the point.
Patient: App in Oracle APEX 18.2.0.00.12
Issue: when I try to create user using procedure "apex_util.create_user" I got error:
APEX - User ADMIN11 requires ADMIN privilege to perform this operation. - Contact your application administrator.
When I go for Manage Users -> ADMIN11 -> Account Privileges I see here:

When I try to use this procedure in SQL Developer I got the same error...
What else I have to set or change to let users create new users? I need to create users outside of apex - just in PL/SQL. I found some informations that developers made some undocummented changes in security, in APEX 4 everything works. This is the only thing which's blocking my app migration to APEX 18.