A NetSuite User of a company cannot see the Fulfill button on the Sales Order, considering that he is an Administrator and Advanced Shipping Feature is enabled.
For the Fulfill button to appear in the Sales Order page with status of Pending Fulfillment, considering that he is an Administrator and Advanced Shipping Feature is enabled, here's a workaround:
1. Navigate to Setup > Accounting > Accounting Preferences
2. Go to Order Management Tab > Fulfillment Section
3. Set Fulfill based on Commitment = Ignore Commitment
4. Click Save