@Mega_Spud (Jay Wells) For me, actually, it was doing that that caused the issue. I was trying to fix another unrelated issue (I forget what it was), and so I cleared the cached content, and deleted the world template so I could redownload. When I tried to redownload, it showed the blue exclamation mark and is stuck "downloading" (although constantly on 0%). If I try going to it's page on the marketplace, the area that would normal have the "download world" button, the "downloading world" bar, etc., it's totally blank and just grayed out.
I don't know about anyone else, but it randomly out of nowhere fixed itself for me. I didn't do anything, I just went onto the Marketplace, found the blue exclamation mark was gone, and I was able to re-download the maps, no problem.