Derelict Mansion: cannot enter boss room

While in a Derelict Mansion map, I was unable to enter the boss room.

I experienced a game freeze before I got to the boss room, which eventually stopped. But Whenever the game freeze happens, it always erases my explored minimap and apparently bricks boss doors. The door or doors that should have opened into the boss room didn't have any clickable element to allow me to get in. So I couldn't fight the bosses and just failed the map =(.

Similar issue without the freeze. Sucks clearing all the waystones just to be locked out of the boss

Edit: There's an item (looks like a lore book) I had to click upstairs to open the boss room. Guess it wasn't bugged for me at least.