Post field with select advanced - search doesn't work well

Hi,

I'm using the latest version of MetaBox (5.3.9).
I've configured a "Post" field using the select advanced option.
I've set up "clone", "clone_sort" and "ajax" to true, with a query args for a custom post type and a custom taxonomy, as you can see:

array(
    'id'         => $prefix . 'protocols',
    'name'       => esc_html__( 'Protocols', 'alomone' ),
    'type'       => 'post',
    'field_type' => 'select_advanced',
    'post_type'  => 'support', // custom post type
    'clone'      => true,
    'sort_clone' => true,
    'ajax'       => true,
    'query_args' => array(
        'tax_query' => array(
            array(
                'taxonomy' => 'support_cat', // custom taxonomy
                'field'    => 'slug',
                'terms'    => 'protocols',
            ),
        ),
    ),
),

The problem is that the search function of the select2 library is not working.
When typing in the search bar, it always says "no results found".
It is working when the 'post_type' arg is set to 'post', but still, it's a bit buggy: it first shows "no results found", and after 5 seconds the result is shown.

See the dropdown loaded on init with ajax:
https://prnt.sc/11smy8z

And then trying to search but no results found:
https://prnt.sc/11sn0uk

Thanks,
Aharon