Level is not necessarily important.
Luxury vinyl plank not sitting flat.
And i don t like it.
That is my semi educated guess.
Even though the first reason for the invention of vinyl planks was to mimic hardwood floors today it authentically mimics different textures colors and species.
You can seal vinyl plank completely and prevents moisture from going into the floor.
When not installed on a level surface a luxury vinyl plank floor can shorten in length when it rides over high and low areas and it can also lift on edges or ends where a substrate irregularity.
Vinyl plank is water resistant and is not like hardwood which is not resistant to water.
During installation run a vapor barrier under the vinyl plank flooring to help prevent.
Your floor is not flat so the flooring is holding itself up by it s own will and when you walk on it you are pressing it down into those valleys and it s touching the concrete.
After all a floor can be flat and have a plane to it.
If water seeps up under the flooring from an extremely moist concrete subfloor the adhesive can be weakened causing buckling in the floors.
The luxury vinyl materials are less likely to buckle than some of the less expensive economy tile floors.
Floor prep the only major rule for installing vinyl plank floors is that the surface needs to be flat.