Hi, me again. I know I'll either get no answer, or a snotty one, but maybe something will happen. If I use the JQuery Migrat Helper as you recommended, I can't configure the Hero Slider in the Customizer. Maybe there will be a proper fix sometime.
skull77
This​ may be due to JavaScript errors or conflicts most likely caused by another third-party plugin​ or customization you have. You need to diagnose JavaScript issues on your end and find out why the featured image is NOT showing in the single page view.
More information can be found on WordPress.org codex page: https://codex.wordpress.org/Using_Your_Browser_to_Diagnose_JavaScript_Errors