Time: Around 1:40 AM EST on 11/4/2016
Frequency: Always (confirmed by others)
World name: Diabolos
Character name: Alukah Bast
Retainer name: N/A
NPC name: N/A
Monster name: Edda Blackbosom (and Nybeth Obdilord)
Class/Level: Paladin level 60
Party or solo: Solo
In-game time: N/A
Area and coordinates: The Palace of the Dead Floor 50 (and Floor 100)
Housing: N/A
Steps:
1. Enter Palace of the Dead as a solo fixed party
2. Clear from floor 1 to floor 50
3. Upon clearing floor 50 the achievement is not received, contrary to what the achievement description says.

Notes: Other users have reported that the achievement is received if the player dies in floor 51+ after clearing floor 50, and other users have also reported this issue to happen with Pal-less Palace II wherein the achievement is not received upon clearing floor 100.