Reaper's Rewards Event: Ambrosia Society Letter Quest, Mailman Frozen

For the Reaper's Rewards Event that launched today, one of the first quests is to receive a newsletter from the Ambrosia Society.

I have already received the letter from the Ambrosia Society and opened it. (notification image attached) However, the quest is not completed and now the mailman is frozen and repeating the 'wave' animation with the thought bubble of the mailbox. (image attached)

Force resetting the Mailman simply makes him leave as if a guest at my house with the notification "I should really get going now. Thanks for hanging out with me. See you later." 

I'm on PC and I've just updated the game. Closing and reopening the game doesn't seem to fix this. I realize this just launched and this is probably a bug, but if anyone has a workaround let me know. Thanks!