cam flat
I have only had 1 cam do that and it was an error on my part.
Comp Cams replaced the cam and lifters before i discovered the real problem. Luckily I did see it before wasteing another cam.
When I installed the rear cam bearing "freeze" plug, I accidently mushroomed it in slightly. This pushed the cam just far enough forward that the lifters were centered on the cam and did not spin as they should while running. Looking down the lifter bore in the block the cam should NOT be centered with the bore.