Before you go much further in your troubleshooting efforts, there are some published Known Issues you should search first, in order to rule them out. Also, determining what type of problem you are experiencing, is very useful.

1. Check Known Issues in Known Issues for Oracle Database Cloud Schema Service for any known problems and solutions that could help you resolve your problem with the service.
2. If the problem is related to the service and is not related to Oracle Application Express or an Oracle Application Express application, then see Resolve Issues with Oracle Database Cloud Schema Service.
3. If the problem is related to Oracle Application Express or an Oracle Application Express application, then see Resolve Issues with Oracle Application Express Applications.