Answer by janh for Why is my WP Query not returning first result's post meta?

    $show_date = get_field('show_date');    $show_venue = get_field('show_venue');    // print '<pre>';    // print_r($show_date);    // print '</pre>';    $query->the_post();

You are setting the active post AFTER getting the values.

Put $query->the_post() always at the top of that while loop, so that the other functions can rely on the global $post variable being set correctly.