Backpack auto pulling

 When players are clicking on SORT from the inventory, it is pulling loot from the backpack to the main inventory 

Dump/send from backpack is off in config

I'm using Backpacks ver 3.17.0 from WhiteThunder 

so it's moving loot from the backpack to the player inventory, I assume the backpack has more items than the inventory? the way the plugin is setup is that it's supposed to do the organizing starting from the player inventory and overflow to the backpack. Is that correct?