Sounds like a bug. If you aren’t on Honour mode, you could try reloading to see if anything changes. If that isn’t working or you are on honour mode, you could go fail a puzzle in another room, which will create a horde of enemies. The good thing is though, if you fight your way through the horde to the door leading to Ansur, it should now be open and you should be able to get to Ansur. That’s how it worked for me anyway.
No. I'm not in honour mode. I will try in another room. I reloaded my save starting in front of the statue before starting the fight but nothing changed. I could load another previous save and starting from another puzzle. Yes i realized the door is open, but i don't know if solving puzzles gives you some interesting rewards more.