Date & Time: Ongoing since 6.3
Frequency: Constant

World name: Sophia
Character name: All characters (occurring for everybody I've asked who's tried this quest since 6.3)
Area and coordinates: Ul'dah - Steps of Thal - The Coliseum - X9.8, Y11.2

Steps:
1. Accept quest "Unholy Matrimony" from NPC Bobonima
2. Travel to the Steps of Thal and begin interacting with "Exposed Walls"
3. Cannot hang poster at coordinates. Other two posters can be hung without issue.