We recently release a new version of Gwangi. Updating your theme and all the required plugins to the latest version should fix this issue.
To update your theme, you can download and install the Envato Market plugin (https://envato.com/market-plugin/) on your WordPress site.
Once the plugin is installed and activated, go to “Envato Market” in your admin menu and follow the instructions under “Activate Envato API Connection”.
When this is done, you will see your purchased themes under the “Themes” tab and you should be able to update your Gwangi theme from there by clicking the “Update available” button.