Can you check if property "glide.sc.enable_order_now" is set to true in prod? (https://support.servicenow.com/kb?id=kb_article_view&sysparm_article=KB0961833)

Otherwise the last thing I could find was about having a current.update() in a business rule on sc_req_item, but it is a very old, but maybe if the above can't help locate the issue, then this might: https://support.servicenow.com/kb?id=kb_article_view&sysparm_article=KB0725630