please note that with Patch 8, we had a change in how the market mails work. They now work like:
Notifications are now only sent when a Buy or Sell Order is completely fulfilled or expires
These mails contain a summary of all relevant transactions, and notifications are no longer sent for every single transaction
Which means you put up 10 items to sell in an order -> you sell 5, receive money for 5 -> buy something else, give away silver, etc. -> sell 5, receive silver for 5 AND receive the market mail that you sold 10 items with the total amount of silver gained.
With buy orders it's similar: you put up the buy order and the silver, and then over the time the buy order gets filled with the items being in the Completed Tab. Once the order is filled completely, you will get the mail.
In this case, could it be that you picked up the missing maps accidentally while picking up other items from the market?
If you're sure you never received the appropriate amount of items, please message firstname.lastname@example.org so they can check it out.