Amazon Free Returns Not Providing Free Label To Buyer

Hi, We sell clothing so all our listings now offer free returns, not ideal but nothing we can do about it so we just put our prices up a bit to cover this.

The issue we are regularly seeing is buyers are being asked to pay for their return label despite it saying free returns on the listing, this obviously causes issues between us and our buyers as this is out of our control, is anybody else seeing this? I didn’t know if it was being caused by the buyer selecting the wrong return method (Hermes instead of Royal Mail for example)

Any thoughts?