The reproduction of SEE should be expected to be difficult because it is rare. If you imagine, for example, that it requires the powder to separate into two piles, one of which provides the fusing heat for the other then the detonation heat for the other when fusing pile no longer absorbs heat by melting, you can see how a lab might never reproduce that situation accidentally within a reasonable number of rounds. They'd have to know that was what they were looking for.
Rocky Raab says the notion that a lab can't reproduce the phenomenon is out of date, and that powder people he's talked to have been able to reproduce it in more recent years. I don't have any references for this other than his say so.
Ignition of the surface area of powder is something that appears to show up in the old Lloyd Brownell study. Plots of erratic pressure with loads below about 60% fill show up in it, though none of his exhibited dangerous pressures. They may well have been due to large surface area ignition, though. (See pages 53 and 54 (64 and 65 as Acrobat reader counts pages),
here.)