we emailed with the customers and they really did not receive the item.
We had in the time frame about 400 like that.
Besides the buyer getting annoyed, amazon keeps the pick and pack fee that was about 2500$ so far. Because they blame the carrier, but as it turns out it was just not one carrier.
My guess it has to do with data transfer from FBA to the Carrier and the carrier is receiving the wrong data.
It slowed down significantly, but it is still ongoing. We went from 2-3 a month to 80. Tried to raise the concern with Amazon but nothing came out of it.
Seems that is just a part of doing business with FBA.
Thanks for your input.
I was sure this must have effected several sellers, but you are the first one responding to that.