I've noticed that Gametracker counts the server size number wrong on the BF3 servers that runs the gamemode Rush with more than 32 players.
Gametracker show that these servers have only 32 slots, when they have more than that as you can see in the "Online Players" tab.

I've picked 3 servers that has 48 slots and have in their maplist some Rush maps (Gametracker shows that these 3 have 32 slots):
http://www.gametracker.com/server_info/62.21.98.153:25207/
http://www.gametracker.com/server_info/189.84.18.44:25510/
http://www.gametracker.com/server_info/195.122.135.41:25200/

I'm sure you are aware, but GT cannot fix bugs in the BF3 software unfortunately. You'll have to wait for a game patch to fix it.