Sales Order with Custom Form has Gross Amount Column Field Greyed

Scenario

The user would like to check the Gross Amount field in Sublist Field tab on Custom Transaction Form of Sales Order, but the field is grey and cannot be checked.

Solution

To have the Gross Amt field visible on the Custom Form, the Tax Code field has to be checked.

1. Navigate to Customization > Forms > Transaction Forms
2. Click Customize/Edit by Sales Order form
3. Click Sublist Fields tab
   Tax Code > Show: Enter Checkmark
4. Click Save