Autocomplete's dependencies are not resolving and are leaving the CSS in a broken state.

Attempting to include only autocomplete widget:application.js has//= require jquery-ui/widgets/autocomplete andapplication.css.scss has *= require jquery-ui/autocomplete results in

And theui-helper-hidden-accessible div is visible.

If you include all of jquery-ui in those files it instead looks like this andui-helper-hidden-accessible div is hidden.

Functionality seems to work fine, so it may be a CSS only problem