Spirit Sentry killing Pumpkin Spirits makes them not drop anything at all

Even if you hit the mob and deal damage to it, if the final damage is done by a sentry grim, heavy grim or any of these, it will not drop anything, and it happened twice with me and ive also seen other people saying it

IMO, they should be listed as ""neutral"" for the grims so only we can attack them or at least make them drop the godamn spirit, im rlly mad rn cause the elder spirit seems to be a lot rarer now and ive just lost one to this >:(