Isolate bug

If you isolate someone who is say...hidden, they stay hidden. On water, in forests (thief is who I tried it on) This is not only abnormal, but a bug for sure. If you say by design, prepare for the open sea/ ranger recall blackjack team! ...but I didn't do that. Just don't say "By design" is all! Stumbled on it by accident, and was told "sounds buggy" so I wanted to report it right away. Ok, thanks.