Responsive designs currently aren't supported in some mobile clients, such as Gmail on iOS. This means the standard desktop experience is delivered. However, your mobile designs will load in mobile clients that support responsive (e.g., emails opened in Apple Mail on iPhones will display responsive designs).
We believe that the Gmail app and other mobile apps will support responsive design in the near future. Once they do, your responsive emails created in Inkbrush emails will correctly load in these clients.