Did you ever find a resolution for this? Having the same issue here.
My problem was that I wasn't refreshing the home page correctly. I had to slide my finger down all the way down on the screen (where the refreshing "wheel" goes around in a full circle). Before that I was just sliding it down halfway causing the icons and maps to not refresh correctly. Didn't seem intuitive at first.
Thanks Jesse...I refreshed a few times, logged out/in a few times, and eventually the thumbnails updated. Still not sure exactly what was caching the old thumbnails, but apparently you just need to be more stubborn than the app, and eventually the thumbnails will refresh.