WP_Query sort by ACF date field (newest first) with blank dates first

Question

I have a custom date field that is optional. If a date is not provided, the item should be first in the items returned by WP_Query. Example:

1st: entry with no date
2nd: entry with date 1 March 2023
3rd: entry with date 1 February 2023
4th: entry with date 1 January 2023

These are the args I'm using:

'meta_key' => 'custom_date',
'orderby' => array(
    'date_empty' => 'ASC',
    'custom_date' => 'DESC'
),
'meta_query' => array(
    'relation' => 'OR',
    'date_empty' => array(
        'key' => 'custom_date',
        'value' => '',
        'compare' => '='
     ),
     'date_not_empty' => array(
         'key' => 'custom_date',
         'value' => '',
         'compare' => '!='
      )
),

However the order is showing with the dates in the wrong order:

1st: entry with no date
2nd: entry with date 1 January 2023
3rd: entry with date 1 February 2023
4th: entry with date 1 March 2023

It seems the second orderby clause is having no impact. I have checked that the date clause works fine when I remove the first clause.

Answer 1

I ended up using these WP_Query arguments:

'orderby'    => 'meta_value',
'order'      => 'ASC',
'meta_key'   => 'custom_date',
'meta_query' => array(
    'relation'    => 'OR',
    'date_clause' => array(
        'key'     => 'custom_date',
        'value'   => date('Ymd'),
        'type'    => 'DATE',
        'compare' => '>=',
    ),
    'date_empty'  => array(
        'key'     => 'custom_date',
        'value'   => '',
        'compare' => '=',
    )
)

For my use case I wanted to list upcoming events (but not past ones). For year-round events these had no set date and I wanted these at the top.