PIles of loot not combining into drop bag

I am not sure if this is how the plugin is designed to operate or if it is a bug specific to my server. 

The main issue I am having is that piles of items that are all different items, wont combine into a drop bag.
In the screenshots attached, it has piles of different items all together.

I have configured the plugin to do:

 "Max drops before moving items to container": 5,
  "Time to wait before moving items": 15.0,

Just want to make sure this is how the plugin is supposed to operate or is a bog on my server. 

Edit: If I pick the items up and then drop them from my inventory onto the ground again, they go into a drop bag properly, It seems to be specifically when the loot drops from a lootable object.

Thanks! Love the plugin otherwise as we have people who craft a lot and it combines those items perfectly.