Can’t get jquery to work in Admin

I have a custom metabox for posts which I need to be a date field on the backend for editors.

My plugin starts with the following code to enqueue jquery:

function load_datepicker() { 
    wp_enqueue_script('jquery-ui-datepicker');
    wp_enqueue_style('jquery-style', 'https://ajax.googleapis.com/ajax/libs/jqueryui/1.12.1/themes/smoothness/jquery-ui.css');
}
add_action( 'admin_enqueue_scripts', 'load_datepicker' );

But it does not work – my field shows up but the datepicker does not show when you click on it.

However, if I activate the classic editor plugin my code works perfectly.

What do I need to change to make this work in gutenberg (without the classic editor plugin)?