Nope, best of luck getting it resolved :(

Why is this happening and how can it be fixed?

If the hardwood is down your not going to fix it now more than likely.

Well if the house is out of level, they would have to raise one side of the house..... Otherwise they would have had to sister leveled floor joists to the exisiting before the subfloor and finished floor to get it level.

You can measure how out of level it is by raising the one end of the level and measuring the gap with a tape measure.

This leveling issue is in the upstairs master bedroom. It's caving in towards the center of the room. The problem is downstairs is one big open space. Can that be it?

Is this the only place where it is not level? Have you checked all the other rooms? I would have the GC check it. If it is not level, even though the hardwood has been installed, I would think it would be on the GC to fix it at his cost.

Where are the load bearing walls or beams?

If you open the plan it should show.

No, that level isn't acceptable. It could also be a good 2' level resting on a high crowned joist. I'd bet one of your parallam's isn't properly supported. Get a laser level and check a few more locations.

Have you tried the old 'marble roll' test? Is this noticeable to you by eye? Could some clever work with the baseboards conceal this? (Since you doubt the floor will be pulled up and relaid, I'm wondering just how bad it is.)

I will try the marble test. Just place the marble on the high point and see if it'll roll?

Do you have construction photos of this area during framing and the beams and supports that are supposed to be holding this open floor plan up? For peace of mind, you might want an engineer to meet you at the house to look at the structure and at any photos you might have.

Not acceptable; the level looks poorly cared for and dirty. I suspect tool abuse. I'm calling the authorities.

Casey

I don't have photos of this area during framing.