WP_Query does not filter results - php

Question

Spent 3 days trying to get the WP_Query to work with Elementor, however had no luck so far. Elementor either refuses to process the query or does not filter the posts at all. Can somebody help me and point out some mistakes that I have in my code?
Context: the query looks for current WP user's enrollment records of post_type 'tutor_enrolled' in 'wpv1_posts' and collects IDs of user's enrolled courses into $course_ids[]. The query should then filter only the posts with IDs matching the $course_ids array, therefore displaying all of current user's courses on Elementor frontend.
function custom_query_callback( $query ) {
$current_user = wp_get_current_user();
$args = array(
'post_type' => 'tutor_enrolled',
'author' => $current_user->ID,
);
$enrollments = new WP_Query( $args );
if ( $enrollments->have_posts() ) {
$course_ids = array();
while ( $enrollments->have_posts() ) {
$enrollments->the_post();
$course_ids[] = get_post_field( 'post_parent' );
}
wp_reset_postdata();
$args = array(
'post_type' => 'courses',
'post__in' => $course_ids,
'posts_per_page' => -1,
'orderby' => 'post__in'
);
$query = new WP_Query ( $args );
}
}
}
add_action( 'elementor/query/custom_query_callback', 'custom_query_callback' );
I tried calling get_course_ids() and custom_query_callback() as two separate functions and trying to pass the $course_ids array in $query->set( 'post__in', $course_ids );.
Then I also moved the variables outside of the function, ending up with:
$current_user = wp_get_current_user();
$args = array(
'post_type' => 'tutor_enrolled',
'author' => $current_user->ID,
);
$enrollments = new WP_Query( $args );
if ( $enrollments->have_posts() ) {
$course_ids = array();
while ( $enrollments->have_posts() ) {
$enrollments->the_post();
$course_ids[] = get_post_field( 'post_parent' );
}
wp_reset_postdata();
}
add_action( 'elementor/query/custom_query_callback', function( $query ) {
$query->set( 'post__in', $course_ids );
});
None of the above resolved my issue and kept causing errors in Elementor.