I've got a couple of media tiles (static image with 10s refresh time). I've noticed that when I first load up the panel the initial image is one from several days ago - it takes until the first refresh (i.e. 10 seconds) to load the correct image. Also, every so often on a refresh cycle it reverts back to the 'old' image for one cycle, before properly refreshing again.
Customer support service by UserEcho