I installed 2.1.2 from source and the queue manager works. Are you right clicking the torrents and select "Enqueue"or "Start"? Because I never tried the enqueue option only start and stop also setting like you the maximum torrents.
Maybe you should drop a visit and a post to ktorrent's forum too...but now I see you already did
Try compiling from source like the dev told you
Cheers,
Vangelis