I know BB do not support blocking, but I have done this adventure twice, once with blocking and once without on this particular adventure in the last few days.
This camp continues to remain after killing all leader camps surrounding it. I have lost a load of elites blocking the other camp to get rid of it, so also tried without blocking, and the camp still remains.
IT IS A BUG.
http://prntscr.com/3r4ows
edit - reported to support 9.6.2014 15:40pm UK time