AJAX refresh removes the widget title

I’ve noticed that when refreshing the widget after an AJAX add to cart button trigger, the widget title is not generated at all.
Sample sidebar registration array to test this out:

array(
        'name' => __('Domyślny', 'callisto'),
        'id'   => 'default_sidebar',
        'description' => __('Domyślny panel boczny', 'callisto'),
        'class' => '',
        'before_widget' => '<div id="%1$s" class="sidebar-item clearfix %2$s">',
        'after_widget'  => '</div>',
        'before_title'  => '<div class="main-title clearfix"><p class="custom-font-1">',
        'after_title'   => '</p></div>'
    )

The widget title (if set in WP admin panel) will not be displayed after making the AJAX refresh.

https://wordpress.org/plugins/woocommerce-dropdown-cart/