Rek'sai Bug

Was just in a game with a bunch of friends and playing a normal game. Everything was normal until we saw a tunnel. My adc saw it so he want to get rid of it first. But for some reason it wouldn't work at all. Even after standing off of it and going back and trying. So went to stand on it to destroy it, but the same thing happened. We eventually kept trying this with the entire them and it never worked.

Also to note the white cooldown bar was black 100% of the time.

The tunnel was near bot tower from the bush to the river edge as close to getting to bot lane as possible.