This is most likely due Order Splitting rules set up by the Brand.
When Order Splitting is enabled, the order minimum requirements apply to each Split Order individually, instead of applying to all items in your Working Order. Most commonly Order Splitting rules are based off of each Delivery Window, so we would advise adding more product under each separate delivery window to meet the set requirements.
You can contact your Sales Rep for more information about the Order Splitting and minimum/maximum rules set up by the brand, for instructions on locating contact information for your Sales Rep, click here.