There are a couple of possibilities here:
- Go in to the Full Details of the Sales Order and check to see whether Single Delivery Order has been ticked by mistake.
- Look in the Company Location to see whether Despatch Full Orders Only has been ticked.
In either case you can over-ride the setting if you need to get goods despatched
Movements -> Despatch
Click on Available Items
Tick the box Ignore Single Despatch Status
Click Search to display the lines