Tailraider Safari bug with monsters that drop Inferno Sac

[Teddy]

I have a weird issue with my Tailraider Safari: Whenever their hunt includes a monster that has Inferno Sacs in its loot table, that is the only thing that monster yields. Doesn't matter what monster or area it is. If it can drop Inferno Sacs, I always get three or four stacks of two Sacs each. Latest example [imgur.com] from today. Since this happens without fail, I'm ruling out bad luck at this point.