Experienced wood floor pros, I need advice.

[Billbill]

Hey guys. I've posted about different questions I had about my prefinished solid oak 2.25" hardwood floors (installed in 2001), and have since gotten used to all the popping and squeaking as this is normal for the most part. That could also be from previous damage (previous owners),that's irreversible so it's not too bad and we've gotten used to it. But after studying into it a little more I was wondering Why one spot would have a slight buckle (near corner of oven and sink), when the board next to it has a large gap (see pics). Our little fridge magnet hydrometer always ranges between 17-20% in winter, ya I know lol, and about 33-41% in summer. I know buckling can either be caused my moisture underneath but can also be caused my high humidity as the boards expand and push on each other but that doesn't really make sense because the boards right next to that area have gaps, some almost 1/4" that they filled in with some dark, soft putty-like material. So I guess my question is, with all this information provided, why would we have such large gaps in some areas and just a couple boards over, have some slight buckling????
Second question is, why so many gaps? Again I thought gaps were caused by dried shrinking wood and its summer! It's not even dry in the house! See pics below please. Buckled right by gaps and some boards have these cracks on the end. Maybe just past owners had the place too unstable? Idk

 

[Ernesto]

I'd say without being there and checking with a wood meter it wasn't acclimated properly. May have been a leak in kitchen as well.
Can you get under it?

 

[Billbill]

I'd say without being there and checking with a wood meter it wasn't acclimated properly. May have been a leak in kitchen as well.
Can you get under it?

Nah I cannot get under to see the subfloor basement is fully finished with drywalled walls and ceiling. My mechanical room in basement has unfinished ceilings that partially exposes the bottom side of the plywood and it's not stained and looks healthy. I figured if it was ever fully saturated that plywood would be discolored in basement but it's not. I pulled a floor register out that's in the kitchen with hardwood and there's some kind of brown paper that's under the hardwood floor. Not sure what that is.

 

[Tristin Hebel]

Color puddy my friend is ur only answer unless u try to pull the boards tight and topnail (in which u will still need the color puddy)