Employee field does not appear on Purchase Order form

Standard Employee field is not displayed on Purchase Order form, although it is checked to be shown on Edit screen of the Purchase Order form.

To expose Employee field on Purchase Order form is needed to have "Purchase Requests" Company Feature enabled. Navigate to:
1. Setup > Company > Enable Features.
2. Employees subtab > Time & Expenses section.
3. Ensure that "Purchase Requests" feature is enabled.
4. Save.

Note: Be aware that Employee field is still needed to be marked to show on certain Purchase Order form.