Hey Anglozone, I’d found that too - but we’re getting the error “Warning The fulfillment-center-id field heading is invalid, so values in this field were ignored” if we now try and add it in. Sadly, then followed by the error description “A value is required for the “fulfillment_center_id” field”.
This error only started yesterday and I can’t find any reference to relevant changes to the POST_FLAT_FILE_PRICEANDQUANTITYONLY_UPDATE_DATA feeds call.
I’m getting the same error via seller central if I try and upload too.
Feels like a problem at Amazon’s end, but no idea where we get in touch with them about it. I’m not going to waste my time with SS.