Greetings! I am sorry if this was just an isolated issue, but I could not forfeit any quests that I have accepted. In my case they were Maple Island quests. I was pressing the button and nothing was happening for all of the quests.
I haven't had the problem myself, but I do know the button can stop working if you hold it over the chat bar, any chance you did that? Also sounds like you are not having this problem anymore?
Not the same problem, but I never noticed that! Pretty sure it's because those event quests have an expire date, but they aren't automatically removed right now.
You are right, I can forfeit quests as long as the chat window is high enough in the screen. I do not know if you still consider that as a bug. I guess you can close this thread, my apologies.