noticed this for quite some time now. I'm not sure if it's a bug/malfunction or it's simply intended to be that way. I often prefer to not hunt for items with Frostprey on for this reason, and it'd be super cool if it would pick up the items monsters killed by it drop alike. best regards, hugs forever! ♥
This was an update some time ago to prevent summon farming - you'll have to pick up the drops manually if your summon happens to kill the mob.
oh. it makes sense now. I remember bishops and bowmasters afk farming for lucky charms over at leprechauns with bahamut/phoenix. in that case turns out to be a good update. thank you Nerd!