Widget Stuck on Load After When Selecting Location

I’ve been having this issue for a while. I have two instances of the same site, one for development and a life one. The plugin works fine on the development site. But on the live site, when I click on “Sidebar Location” the widget freezes and gets stuck on the loading screen until I click away. I haven’t been able to add new sidebars.

I checked the console and this is what I found:

widgets.php:32557 Uncaught TypeError: settings.data.search is not a function
    at HTMLDocument.<anonymous> (widgets.php:32557)
    at HTMLDocument.dispatch (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-widget,jquery…:3)
    at HTMLDocument.r.handle (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-widget,jquery…:3)
    at Object.trigger (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-widget,jquery…:3)
    at Object.a.event.trigger (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-widget,jquery…:9)
    at y (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-widget,jquery…:4)
    at XMLHttpRequest.c (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-widget,jquery…:4)

Has anyone else had a similar issue, could you please help me?