There is a field "Incumbent" in Position object definition. Even when an incumbent is assigned to the Position, still the "Incumbent" field does not show the user and it remains empty.
Reproducing the Issue
Configure Position object with the field Incumbent and it's visibility as Read Only / Editable. Create a Position / search for a Position to which an incumbent can be assigned. Assign an incumnet to this Position. Still, the "Incumbent" field remains empty.
It is an expected behavior. The "Incumbent" field isn't used by Position Management. This means that the field is never changed when you assign an employee to a Position. Only the jobInfo of the employee is updated in this case.
The "Incumbent" field is used by Succession Management. If you use only Position Management, then it would be better to make this field invisible (visibility = Not Visible).
If the "Vacant" field value of the Position should be changed when assigning an employee to a Position / when removing the employee's Position assignment, then you have to make the related settings in the Position Management Settings UI for the following options:
1. Reset 'To Be Hired' Status if Incumbent is Assigned to a Position
2. Set 'To Be Hired' Status if Incumbent is Unassigned from a Position
Incumbent, Position, Update. , KBA , LOD-SF-EC-POS , Position Management , LOD-SF-EC , Employee Central , Problem