Very new to the group and new to hardwood floors however I have done my due diligence in research and from what I have read my problems are more than "natural" wood movement and actually a bad install. Any professional help with this would be great. We have only lived in the house since September 15, 2018 and moved in right after the home was completed. About every 2.5-3' we have these pretty big gaps that run the entire length of the room and make the floor look aweful, they have wood filler that has cracked and fell thru, they seem to have smeared wood filler in quite a few of our "natural knots" and look awful, some of the planks have started to crack where I can press down and see movement where it has cracked all the way thru, and there are sharp edges where pieces of the floor have dried and broke off. I will attach several pictures so you can look at it and give me some insight. I have to meet with the builder and the flooring company Monday so would like some guidance on what to tell them. My wife and I want a new floor because we feel this will be a continued problem with this floor even if they try to repair. Thoughts? PICS WILL BE POSTED BELOW I HOPE

What species and grade is this flooring 'supposed' to be?

I would have trouble calling this done in a workman like manner. The filler looks sloppy. Some universal color should have been mixed into the filler to get a closer color match. Paint stores have it. You may have some shakes in the floor which will need to be replaced. If it looked good when you moved in then shrunk, it may be from the winter heating season and will expand during a moist summer, unless you use an air conditioner.
The flooring may have been too damp when it was installed.
The sanding job doesn't look bad, but there looks to be over wood in spots.
Sorry.

I'd say you have a moisture issue under the floor. Whats under it, basement or crawl space?