Check if the "Available To Promise" feature is enabled.
1. Using Administrator role, navigate to Setup > Company > Enable Features.
2. Go to Items & Inventory tab.
3. Under Inventory section, check if Available To Promise = T.
When users enabled the Available to Promise feature, they can check the future availability of an item. User needs to assess the availability of the item first before the expected ship date will be populated. Here are the steps:
a. On the Sales Order page, select any assembly or inventory line item.
b. Click the Expected Ship Date field.
c. Click the Check Item Availability icon (small yellow box).
d. Check if the item is available.
e. Hit OK.
f. The expected ship date will now be populated.
If user wants the expected ship date to be populated automatically without checking each line item, they can just disable the feature.