Once the Delivery Box is full and an Artisan still has a order, the artisan will take the comission/ressources but stop because the Delivery Box is full. After the Delivery Box is emptied the Artisan will continue its order but again take the comssion/ressources.
How to reproduce:
Give enough ressources/gold for 14 crafts on a character with 12 slots in Delivery Box. Give an order of 14 crafts to an artisan with 100% proficiency. Let the Delivery Box fill and notice the ressources/comission get subtracted for a fake craft. Empty out Delivery Box and see all ressources gone. Wait for the last crafting to finish and have only 13 results.