A Common Scenario for our customers is to set a Pricing Rule Limit Type associated with an Order Campaign and set Min Qty = 1
This means that reps are enforced to save Orders with all Products selected and with at least 1 in quantity.
Mass Entry Mode Enabled Products can be automatically added. However, if a rep does not enter a quantity, the Order record can be saved.
This currently works as designed. In Mass Entry Mode, the lines that the user does not edit are treated as if they are not in the order. The equivalent in Single Entry Mode is not adding the product from the product selector.