Currently when you attack a stack of enemy ships that are on the same tile, when you kill the first ship, the game will not draw the next ship that is in the pile until you click on the tile. When mousing over this tile, the game will show the info card for the top ship but the tile will still remain blank.
http://i.imgur.com/btZE9K0.jpg
http://i.imgur.com/V331IMS.jpg
Clicking on the stack will cause the ship to be drawn.
http://i.imgur.com/lufndAI.jpg