Hello,
I am trying to solve the same round trip problem mentioned in my other post below.
https://community.esri.com/t5/arcgis-network-analyst-questions/round-trips-vrp-arcgis-online/td-p/1024142

I created the same request with one driver but eliminated the route assignments and sequences. I added additional two order pairs . The two additional order pairs have the same geographic locations. The first order of each pair is a drop off while the second is a pickup. I did not specify and PickupQuantities or DeliveryQuantities on the stops so this should work. For some reason the out_stops response parameter returns back empty. All the stops go to out_unassigned_stops. To my surprise the violatedConstraint for all my stops is "MaxOrderCount exceeded" . Why is this the case ? I attached my request to this post for your reference.
Thanks