(Hopefully detailed description of the event will help)
I accidently released Shoggoth to build towers while forgetting about my poor sheep in the sheepfolder nearby. Shoggoth nearly killed them all, I tried my best to save some of them and move them to about 30 blocks away from the scene of carnage. However, Shoggoth has a long following range and ran to the rest of the sheep, so I quickly delievered the Shoggoth Map to it, it then turned back to the work.
After finishing the building, it appears to be clam down, staying at its place. But when I attempted to use my Blackjack to retrieve it, I failed again and again. I tried to quit the world and relogined, but this didn't help. Finally I had to kill the Shoggoth and made a new one.
It seemed like something was wrong with the "calm mechanism". Shouldn't it be seen as calm when it has no trend to attack other mobs?

It's part of the same problem you described in Issue#23. Will be fixed in the next update.