Possible bug found. Got to "Unreadable handwriting - Easter eggs in the desert" and deliberately did not wait to fulfill the trading criteria for the quest, but purchased the "ticket" for the quest from the trader for 10 credits.
Completed the hunt and received the reward.
Then completed the trading criteria for the quest (sold 100 coal / purchased 100 brew). Have now received invitation to do (already completed) quest , quest title box comes up on right side of screen but no further dialogue boxes appear. Cannot do quest again and cannot move on beyond this quest.