I completed this event Friday morning with no problems on Palenque. I tried to complete it with another character Friday afternoon and even though the NPC's still had items available, they said that the exchange service was closed for the day. I do it again Saturday morning with no problems, but get the same 'exchange service closed' message when I tried to do it Saturday afternoon. Ditto for Sunday and today (Monday). It works in the morning but not in the afternoon/evening hours. I didn't see anything in the event announcement that the guild items are only available for a limited number of hours each day.
So what I'd like to know is:
Can you only do it once per day per account? Once per day per IP address? Is it a bug?
If the answer is 'YES' to the first 2 questions, then stating that in the event announcement would've been nice.......