Molten Vault - Boss locked in Phase due to stun

Issue: If the boss is stunned just before using the ability where waves of molten gold spawn flowing towards the end of the tunnel, generally when he initially steps into the molten gold, he gets stuck in the stomping phase and continually walks towards the end of the tunnel.

I was able to recreate this issue multiple times through multiple run throughs. All it requires is stunning the boss as he steps into the molten gold causing the phase issue.