How do hydraulic flat tappet lifters fail?

Yes, they were new. And yes, that’s the rocker end. All of the lifter ends of the rods look perfect. Maybe I got the length wrong? That’s just wishful thinking, because that’s the easiest fix...
Did you measure your preload? That could cause some major problems lunati lifters require. 020-060 preload if the pushrod are too long they would exede that preload. Seems to me it would have bent a pushrod during break in tho. Did you have any bent ones?
Lack of oil would probably cause those dings.