Yep, there are certainly multiple reasons for failures with BH. Whichever one you don't know/do is the primary one for your failure.

One of them saved my bacon once: BHs need for some compression/semi-snug bullet. The ONLY time I have ever short-started a bullet was with BH 209. The primer went pop and the bullet went about 10 ft out of the barrel without any ignition of the powder. I shudder to think if I had done this with another powder. So, sometimes a failure can be a blessing!

So, I did not vote either because there are multiple reasons and all of them stem from lacking knowledge. In my experience, wrong primers and wrong breechplugs would account for 95% of the ignition issues. From what I have seen of these two, they are about 50/50 as to which has caused a person to have issues. I can't vote for one over the other as "primary".