[GAMEPLAY] Indestructible Rek'Sai Tunnel Bug

I played a game today as a top lane Ryze. During one of the opposing Rek'Sai's ganks, she created a tunnel that I found to be indestructible. There was a blank timer on it and no amount of time standing on the mound would break it. The Rek'Sai could still use it as he was able to travel through it and ult to it. She also confirmed that it did not count towards her tunnel count. My teammate Gragas and the opposing Akali also confirmed this bug.