The same has been happening to us for the past few days.   Shipping is turned off in our account settings and on the invoice settings.   The fields will be gone initially, but as soon as I create and save an invoice, they reappear.   To hide them, I have to open the invoice settings, check the Shipping box, and then uncheck it.   Every single time I create an invoice.

It happens even if I use private/incognito mode on my browsers.