I answer approximately one hundred questions a day in different languages and different places (forum, support, facebook, app stores) and a lot of them are the same. I was pretty sure I already have explained the reasons of the 15d leagues here but it seems I was wrong. Sorry about that.
About the empty challenge map, we found a bug today and fixed it. Your map will fill normally now (one new opponent every 4h).
About the empty challenge map, we found a bug today and fixed it. Your map will fill normally now (one new opponent every 4h).