Originally Posted by
Bruschi
It's very clear what happened with the OP's BK....
At the moment that he finishes off the building he was attacking just before the first pic was taken, the closest building to him is the archer tower inside the walls. Once that target is selected, it doesn't matter if other buildings become closer during his journey to it, his target is already selected. The only thing that can change that is either destruction of the target, or perhaps attack by CC/hero.
This is not new. It's how the AI has always worked.