[Theme Horse Support Team]

Hi @thomas-hess,

We have checked your Site URL and we found some of the plugin you are using might have replaced the WordPress default javascript/jQuery file which have affected the sticky script. Please try checking by deactivating the plugins one by one. We have a doubt that the plugin ‘jquery-updater’ might have replaced the default script. But also please check by deactivating every plugins individually.
And also update the theme to a latest version. You can download the latest version from your login account.

Thanks