Haunted Halls of Eveningstar Doppelganger bug is back

[PurpleTimb]

Tonight (10 December 2017) my party became stuck in Haunted Halls after the Doppelganger failed to advance. I thought this bug had been squashed as I haven't experienced it in the last six months or so.

We were in epic elite Haunted Halls Extended Version
Party consisted of a sorcerer, barbarian and Warlock (with aura).

After the doppelganger hid among the statues we were unable to advance the quest. None of the dialogue options caused any reaction from the statues. The "swing your weapon at the statue" resulted in a regular attack on the statue. We eventually attacked all the statues and destroyed them all, leaving us in an empty hallway with no doppelganger and no crest. I opened a ticket and filed a bug report, but as it was after GM hours there was no response to the ticket.

[PurpleTimb]

Interestingly, when I submitted the bug report this is the screen I got after hitting submit, so I'm not sure if my bug report was even filed or not.

[Tist]

It never went away. If a player goes into some kind of large script radius of the doppelganger, and has been invisible in the quest at all, the script will bug out and not progress.
The range is at least to the locked door named fight which can be unlocked by the puzzle.
Temporary invis procs are enough to cause this bug. I have to remember to remove trinkets and cloaks when entering the quest, and go directly to the encounter, to save wasting more time if it fails.

[Cordovan]

There should be a workaround where if it bugs out the crest will spawn after a few minutes of inactivity.