This type of lack of commitment to business hours or operating obligations is not uncommon for this place. At least 3 times I had tried to swing by after working until 8pm on a Mon/Tue/Wedns to find out they had decided to close early.
They post their hours as open to 10pm, but decide to stop taking customers much earlier, like 8:30pm. People would be scattered inside (definitely not private parties, which they could easily post a sign on the door for), and the entrance would be locked.
They've managed to survive, as part of a group of bars (Jackson Tavern, Madison Tavern, pretty sure there are others I cannot recall), but the operation doesn't seem ambitious in terms of reliability.