I found out something about rooms with 14/14. 14 is the max number that people can be inside a ranked team room but sometimes the game doesn't really show the real number. There could be only 13 or less people in there and yet the game is showing that there's 14 people in there. I tried to go inside the 14/14 room and I made it in. There wasn't 13 other people there. So when you a room that is full. It doesn't always mean that the room is really full. Try to go in to check if it blocks you or not.

That might also explain rooms with 15/14

The online was acting weird yesterday. A room with a lot of people keep disappearing all at the same time.