Not sure if this is just me, but I got a lot of new pics when I remove the game and re-download it again from appstore. I am iOS player.
It seems like there are some issue for the user who upgraded all the way from long time ago without re-install the game.
In the meantime, it would be great if there is a “download all” option since it takes a lot of data and time to download all the troop pictures.