Service Provider constraint not passing through to order movement on a multi-stop

I have an issue when trying to submit a service provider on a multi-stop order release. when it goes through bulk planning the order movement shows no service provider constraint on it, and then the shipment plans to a different service provider. I'm guessing this is something to do with the itinerary but I could be wrong. I have primary selected on the itinerary i see that is required for service provider constraints. Any thoughts or ideas.

Thanks