This doesn't surprise me. I know it's a totally different gun and design, but I have one of those totally awful, no good, might as well throw it in a dumpster external extractor Kimbers. It ran fine with factory parts using soft target loads and a light recoil spring. Switching to 230gr ball and HP and an appropriate recoil spring for those loads, it had extraction issues. An extra power extractor spring from Wolff turned it into a very reliable gun.
Just to note that I think it's fairly easy for a company to design a gun with a properly shaped and installed extractor but then fail at selecting a spring for it.
Also, I've probably triggered some dark magic ritual by bringing up a Kimber that works in a thread where people have already mentioned HKs that don't. Whoops.