Can't set dark background color for navigation bar when system has light theme on

Please provide the following:

  1. SDK Version: 40
  2. Platforms(Android/iOS/web/all): Android

When the system is on light theme, if I set the navigation bar background color to #444 in app.json the navigation bar is still white but if I set the set the theme to dark the bar changes to #444. Is this the expected behavior or is it because I’m in development mode ?