Not sure if this will help at all, but I reached out to BMW USA and BMW customer relations regarding the issue. If anyone has time, I would suggest contacting them as well so that they are aware that this thumping sound is NOT normal and other people are NOT satisfied with the current state of things. PM me if you want an email template
Connect with Customer Relations link:
https://www.bmwusa.com/contact-us.html
Also sent email to: CustomerRelations@bmwusa.com