Stuck at 99% map on NG+ and the 2nd Curse letter wont activate

[Gu Khon Thai]

On NG+ with that last option keep items, weapons and altarpieces. This will lead players to unable to activate the Curse letter side quest. When player kneel in the big mirror room of Two Moons's area, The 2nd letter wont come out. So that players cant go to the secret room in Mother of Mothers's area which Helmet was left on the floor. This will get players 99% of the map and completion.

[Innovative Username]

Yep, this has happened to me as well. Very frustrating.

[VOID]

Same here. Annoying that we can't get 100% map completion.

[NEXT]

I too am stalled on this bug.
I don't know how to fix it.

[♫ Zedilian ♫]

Devs just too busy sipping sangria instead of fixing some minor issues.
All is left to hope some patch will fix it.