The tag for maps that pops up when you hover over them, with the map number, the really long map number and the scaling info, etc,, disappears when you store the maps in a chest and restart the game. Instead of the info popup, each map reverts to "Unknown Map".

Once you bring the map into your inventory, the info tag will reappear, and the maps themselves are fine and in the same state of completion you left them, but it makes it difficult to choose which map you need from the chest. I've taken to keeping them in numerical order in the chest to alleviate this.