Not trying to be argumentative here, but why do you think it's necessarily Comp Cams' fault? All of the cores that are used come from about 2 core houses.
Most of the time, when I see someone smoke a cam, it was because of one of these things:
1. Didn't check that lifters rotated freely in bores before putting intake on.
2. Too much spring pressure.
3. Not the correct oil.
4. Cranked it too long before the engine fired.
I hear, "I never had trouble breaking in cams until recently" quite frequently from some of the "older generation". It's because they were used to breaking cams in with factory valve spring loads. Today, if you buy a new set of cylinder heads, the spring loads are WAY over what should be used for a flat tappet camshaft.
FWIW, to this day (knock on my head), I have yet to have camshaft issues. I don't do a ton of flat tappet builds, but I do use them.
When I set up the heads, the majority of the time, I will set the seat loads up below 100 lbs seat and the open loads way under 300. If I have to pull the inner springs out to do that, then I do. If I have to completely swap to another valve spring, then I'll do that too.
Gotta have *quality* engine break-in oil, such as Joe Gibbs, Brad Penn, etc. If you use a regular motor oil, even with some kind of additive, chances are it won't be enough.
To answer your other question, the first thing I'd do is check the filter. If there's not much metal in it, then I would drop the pan and check a couple of bearings. If everything looks good, then I would make a decision on what you want to do with the new cam, then flush the engine a time or two with fresh oil before starting.
Comp Cams seems to get the blame when cams go flat, but it's because they are the largest camshaft supplier that I know of. Obviously, when you look at a statistical bell curve, their failures will be higher just from the sheer numbers of cams they put out, but I would venture to say that most of the time, it's the builder's fault. There are mishaps that can be attributed to the supplier (possibly a bad heat treat, etc.) but generally it's not the cam grinder's fault.
EDIT:
I don't use ProMaxx heads, but I went to their website and looked for spring loads. If you bought their heads setup for a hydraulic flat tappet camshaft, they are advertising 145 lbs seat load. If you didn't pull the inner springs out or change springs for break-in, that's why the cam lobe went flat. They're showing 145 lbs seat and 350 lbs open at .600". Too much spring load for a hydraulic flat tappet camshaft, especially for break-in.