I'm not sure of the number, I didn't think to write it down because I took a screenshot, but the screenshot failed. It happened two times now, at first I thought it was just my connection, but after failing a quest the screen goes black, and then I seem to have a connection error. First it happened on failing the promotion test for the first time, and again it happened on the Quest for killing the seven wise men from the bar.
Edit: I also don't know if this is normal but upon re-entering the game after this bug, I'm able to retry the quest for the seven wise men.
Edit2: Shortly into the quest for the Seven Wise Men, I got the following message. "You have been disconnected from the battle. An abnormal action that cannot be verified was found. Please check whether any other programs are running and that your hardware drivers are up to date."
Edit3: I got the same error about being disconnected from the battle in the quest to save the three brothers, after fighting for about a minute without being able to damage the enemies in the base I was attempting to take over.
Edit4: Oftentimes after performing a musou attack, I find myself frozen in place for several moments. I'm using Lu Xun's dual swords, currently. I don't know if this is a general bug or one specific to the weapon.