Hi @aj1310,
Jsprit assumes Delivery jobs are already loaded at the very beginning of the route, and Pickup jobs are not unloaded until the end of the route, as I explained in this post.
Therefore, in your case, the vehicle has to unload the Delivery job before it can load one Pickup job and is not able to load the second Pickup job, due to the capacity constraint.
Best regards,
He
EDIT:
btw, if you would like to model a job that something is to be loaded and then unloaded during the route, you should model it as a Shipment.