If I don't carry the items in my inventory(marked as drop shipped), it seems obvious to select the type as Non-Inventory, but for some reason, I was told to mark them as type "Inventory". Why? 
Also, in the chart of accounts, my inventory goes down negative, which is to be expected as I don't have inventory for my item, when I post the sales invoice, and once the purchase invoice is posted, it goes back to 0. Which reflects a change in COGS(Items), which is what I need it to do, but that is ONLY WHEN THE item is marked as type "Inventory", when I change the type to "Non-Inventory", there is no change in COGS(Items).

50100 has an Item as type "Inventory"
50300 has an Item as type "Non-Inventory", but I would like it to reflect as COGS - Items as it seems right to be reflected there.