We are using database accounts for APEX INTERNAL workspace authentication.
We decided to switch to runtime environment on simulation and production. Runtime environment works as expected. After a while we switched back to full development environment for a day.
We were unpleasantly surprised - nobody can login into APEX administration! APEX switched INTERNAL workspace authentication to default Application Express accounts. However there is a solution: running apxchpwd.sql. After that APEX instance admin can login into INTERNAL administration. He switched INTERNAL workspace authentication from Application Express accounts back to database accounts.
Next, DBA switch to runtime environment again. Again we have runtime environment with database accounts authentication.