When shipment line is backordered sales order line remains in awaiting shipping status

Summary:

We are using WMS cloud as execution system. In this case e.g. if we have sales order partially allocated in WMS, we are splitting shipment line so that 1 line qty will be equal to allocated qty and other line qty will be backordered.

But in this case we are able to split shipment line but line is not split on sales order.

We have tried running Send Intermediate Shipment Status Update this will only update line status in OM as partially backordered but does not split sales order line.

I have gone through other recommendation on Customer portal but none of the suggestion seems to work.