If the Developer Toolbar (shown below) in your Oracle APEX application is not displayed, you can control its display by changing the Status attribute on the application’s Edit Definition page.
I’ve learned about this when somehow one of our applications suddenly did not display the Developer Toolbar. We found out later that during environment refresh, the deployment team switched the Application’s Availability Status to Unavailable before the refresh and then back to Available after it’s done – not realizing that it was initially Available with Edit Links.
No harm done – just temporary inconvenience from Developer’s standpoint. 🙂