Rek'sai bug - Undestroyable tunnel

I have seen that happen (many patches ago on the new dominion RGM), but couldn't figure out why. After seeing the video, I'm pretty sure it's because she was killed mid transit in the tunnel. I don't believe you can remove them while she is in there (which is why it came back up as undestroyed), and it looks like dying in it made it invincible.