Explosive spear explosion does not count as "hit"

I have been trying to use polcirkeln unique with explosive spear and noticed that it is only the initial hit when the spear lands or goes through an enemy that registers as the Hit for the ability and the explosion afterwards does not. This means that in this case with polcirkeln it is only the initial hit that can shatter enemies if it kills them.

I dont know if this is intended or not but it seems a bit underwhelming for me atleast and I think fixing this would open up some nice builds.