From what I’ve heard from a source in the Dallas area, failure rate is up to about 25% on cams right now. The cores we get from China are junk. I bet it’s the lifters as well. Sell your soul to the devil and it will come back to haunt you.

I've been saying for years, when you nitride a cast iron cam, the process reduces the core hardness of the material. You end up with a very hard, but thin outer layer, but the backing material is now much softer. The hard shell. helps with break-in, but the after a while the softer backing material gives way, and the hard shell starts to flake off. As soon as that starts, your cam is toast.

(On nitriding) Yes, it can make the cam brittle.
And it can also cause flaking on the lobes.

We've been nitriding flat tappet cams for years(I use the same heat treater as my biggest competitor), and I only reccommend it, when there is no other options.