first pf all, please go to
/wp-admin/edit.php?post_type=wppizza&page=order_settings
scroll down to
Item and Cart Updates and Amendments
and make sure you set a style in
“Items update style” if there is none selected for some reason
and even if there is, please simply re-save that page
let me know when you’ve done that please because at the moment i can see a bunch of js errors because of that