Cupped boards are common problems after installation often due to moisture damage or flooring that was not dried sufficiently to start with.
The 5″ piece of Beech Flooring is what a cupped board looks like before planing. Much of the imported pre-finished wide plank flooring has moisture issues. Better to rent a moisture meter and check the ends of the boards for moisture content before putting material down from another part of the world. If it is more than 8% consider returning it for a refund. We have seen pre-finished flooring measure at or above 12%.
I was skeptical when Merv told me that I could put down 1×8 boards without surface nailing or screwing–however it is true. When flooring is dried properly it lasts beautifully.