Marking a MV Order as Shipped in Admin Panel

[dylviz]

I know this will be a bit vague, but I'm having some trouble understanding what's causing this issue..

I have two seller's orders that have stemmed from an aggregate order. I have clicked "fulfill order" for both sellers which shows the fulfillment section with "pending":

This the Request that is made when I click "mark as shipped":

But the only response I get is: ORDER_STATE_TRANSITION_ERROR

From the image above, I can see it's trying to transition to the "shipped" state when I would think it needs to go into the "partially shipped" state. Still looking into it, but haven't been able to find anything yet so i'm hoping for input or suggestions. Thanks!