During Levi EX, me and my friends witnessed a weird bug in Leviathan EX: his HP got reset to full near the end of the fight and he went back to the position and skill rotation that he does at the very beginning of the fight, of course, without the walls around the platform. What would have caused this?

Here is that weird moment on twtch, it happens around 0:13 seconds:
http://www.twitch.tv/anderfernandes/c/4478873