Mobile menu sub menu not working

VR Calendar includes boostrap.js file which Bellevue includes as well, causing a conflict. You can dequeue the VR Calendar bootstrap.js by adding this to your child theme functions.php file.

 * Dequeue the bootstrap js from the VR Calendar plugin.
 * Hooked to the wp_print_scripts action, with a late priority (100),
 * so that it is after the script was enqueued.
function vrbootstrap_dequeue_script() {
   wp_dequeue_script( 'vr-calendar-bootstrap-script' );
add_action( 'wp_print_scripts', 'vrbootstrap_dequeue_script', 100 );

That's it. :)