Based on the image that you provide above, it seems you forget to check Enable Add Media option on the Customizer, but as you said previously on Themeforest comment you’ve enable that option. It’s weird for me. Can you please provide me login access to your WP admin panel into your website? So i can check it directly what actually happened in there. You can send it here and don’t forget to check Set as private reply option below.
Glad to hear that you’ve been found the issue. At the moment we don’t provide the ability for subscriber or contributor user role to able using image uploader for security reason. In this case, you need to change the user role manually to make sure if that trusted user.