I've found a minor bug.
I cleared the Vault in Nephlune before finishing up the Blue Sugar Menace quest (because of the 5 day waiting time, I started it on 41st day lol). I didn't realize there's a quest for that right after.
Starting the next Adventure Guild quest in Nephlune gives a message "ERROR: Tried to close objective with ID 1 of quest with ID 36, but no such objective is registered.".
This doesn't seem to impact anything other than being visual (the quest shows up on my Completed list as usual).