i have this problem. i can only play whatever map that is already in, but beside those. other custom map, eg: Ai Missions map i cant play. and you said once i join the game, while game start i will have the map. but to my case, i cant. i can join the host, but after he start the game, the transfer goes up to 99% and stop there for about 3 to 5 minutes, then exit back to game lobby.
C:\Users\XXX\AppData\Roaming\Command and Conquer 3 Kanes Wrath\MapPreviews (this Location correct?)
i using window 8.1 x64, games get from ORIGIN.