How to solve problem when oracle apex does not let me do anything with my created schemas even though I should have privileges?

I have a problem with with latest version of APEX, I have installed it on my pc, i logged in as and admin created workspace with schema, but when I log in to that workspace as a user with admin's privileges or developer's privileges and try to use SQL Workshop I get an error: > User has no privileges on the schema. Contact your application administrator. When I try create a table with SQL command I get > Schema "DB" does not exist in the database. Please contact your workspace admin to set correct default schema for you. even though user has been assigned that schema and it does exist. When I try to create another schema for the workspace I can't and I get an error > ORA-65096: invalid common user or role name Even when I try create new workspace create workspace I get an error > Error provisioning . ORA-20001: Request 1246482779115523 could not be processed. PROVISION_COMPANY but when I press return and press create workspace again it succeeds for some reason. I have no idea what to do, how to solve this problem, I tried everything in settings: granting privileges, setting default schemas, creating new users, setting role as developers, yet the issues do not go away. Any help is appreciated.