Solid Hardwood, Engineered and Laminate Flooring - Where did I go wrong?

:wall: I was laying 12.3mm laminate in my dinning room and entry hallway. substrate was flat (flat not level!) the dinning room is 9'x9' and the hallway is only a 3' span with an open drop into a stair well on the left hand side, dinning room on the right hand side (facing north; with boards running north to south). Everything was going fine, I did not use a T strip when going from the dinning room as the flooring I am using is a 3" plank and it fit quite nicely and only required a little trim to make it all fit. I got the whole floor laid and when I went to cap off the drop off and the first stair into my sunken livingroom, I noticed that the floor was lifting up on the side closest to the dinningroom wall (about 3' from the opening into the dinningroom).

I was hopeing that I can just hold this tight with stairnosing and all should be good? When standing in my livingroom and looking at it, the top stair is flat, and you just the floor starting to curl up ever so slightly. I noticed this when my wife walked past me and the baseboard moved. Total deflection at wall is 3/16" - and a straight edge placed on the edge of the floor does show a gap while the substrate underneath does not.

Do I lift the entire floor and find why it is torquing up in one corner or do I just glue and nail the stair nosing down and keep my eye on it?

Any ideas are appreciated, sorry for the novel!
Derek

For bigger areas you need a 10 foot straight edge to check flatness of substrates since the spec is 3/16" in 10 feet.

I think you know what you need to do.