meta_query in wp_query not working as expected

It is not working because there is a custom query in the events plugin that adds the posts to be ignored (not returned) when you run WP_Query. See getHideFromUpcomingEvents() method in the-events-calendar/src/Tribe/Query.php. But there is however a filter hook that you can use there to do whatever. See the following sample code:

function wpse283031_hide_ids( $ids )
    $ids = [];
    return $ids;
/* this filter should be added **before** you run WP_Query */
add_filter( 'tribe_events_hide_from_upcoming_ids', 'wpse283031_hide_ids' );

Another thing you can try is add 'suppress_filters' => true to your query args. As in:

$args = [
    'suppress_filters' => true