It seems that SSL was installed on your site after the theme installation, which may have caused the theme options CSS and JS files to not load properly.
You can easily fix this issue by ensuring that HTTPS is set in your WordPress General Settings.
If the issue persists, you can install and activate the Really Simple SSL
Really Simple Security – Simple and Performant Security (formerly Really Simple SSL)
After activation, go to Settings > SSL and click on the Go ahead, activate SSL! button. Once done, check the Theme Options page again.