Platform: Windows 7 Ultimate 64-bit SP1
ISP: Comcast
Type of Internet Connection: CATV
Internet Connection Speed: 68Mbps
Date & Time: Feb. 22, 2015 21:30 EST
Frequency: Once (did not reproduce)
Character Name: Rwolf
Race: HumeM
World: Bismarck
Main Job: Blue Mage, Lv.99
Support Job: Red Mage
Area and Coordinates: Eastern Adoulin, G-8
Party or Solo: Solo
NPC Name: Oston
Monster Name: Not applicable

Steps:

1. I had just purchased Yorcia Visage III and Faithful's Torso III from the auction house around 21:30 EST on 02/22/2015.
2. I walked and did not use any teleportation from Eastern Adoulin Auction House to Oston at G-8.
3. I spoke to Oston.
4. I spoke to Lola. (both just in case I needed to in order to make this key item)
5. I traded Oston Yorcia Visage III, Faithful's Torso III, Faithful's Legs III and Eudaemon Blade.
6. He prompted me for the gil amount and I confirmed.
7. I got a key item obtained message. Yorcia eudaemon.
8. Around 23:30 EST on 02/22/2015 I checked my key items to see it didn't exist.
9. I spoke with Oston to dismantle and only saw a Ra'kaznar simulacrum I had stored.
10. I checked my inventory with /itemsearch for the items I traded.
11. I traded Oston a Yorcia Visage I, Faithful's Torso I, Faithful's Legs I and Eudaemon Cape to see if he would take it since you can't have two of the same key item.
12. He took it and it worked on entry.
13. Observed the key item Yorcia eudaemon that I initially made disappeared. Made from Oston Yorcia Visage III, Faithful's Torso III, Faithful's Legs III and Eudaemon Blade.