Issue with Boss of The Molten Vault area

When I fought the Smith boss in Molten Vault, I died when the lava reached the end of the track but also managed to kill him after dying, and he dropped his quest item. When I respawned at the checkpoint he was there but immediately went into death animation and dropped his quest item again. However I was unable to access the crane to get back into the boss area. I have tried teleporting to town and back, dying and respawing at the checkpoint, logging out and back in, and nothing will make the lift reactivate. I guess I'll need to reset the instance and kill the boss again which is inconvenient but oh well. Hopefully this issue can be resolved. Thank you.

Yea I believe its the problem with every boss not specifically with the molten boss because the map will be wiped after you die.