Query clauses have a few issues that are not documented and you only find them by finding theme.
Query clauses do not work well with nested meta queries. Honestly, I don’t remember if they work at all with nested meta queries.
Query clauses 100% do not work with a nested query that has multiple meta keys associated with it.
// order by true/false field, desc and then date field asc
$meta_query = array(
'relation' => 'AND',
'qw1' => array(
// it does not matter what value this field is
// it is only used for ordering
'key' => 'activi_datumperiode',
'compare' => 'EXISTS'
),
'qw2' => array(
// note that ACF fields not stored as dates in DB
// they are text values (or number)
'key' => 'activi_datum',
'value' => date('Ymd'),
'compare' => '>='
),
);
$orderby = array('qw1' => 'DESC', 'qw2' => 'ASC');
