APP-07599 Supervisor is not valid for the duration of the assignment

Assigning a newly hired supervisor to an existing employee; system only accepts "Update" and changes the assignment date. 

The assignment date is not applicable to the supervisor but to the position/job being held by the employee.

The problem is the supervisor's start date is later than the employee's start date.

In pure business terms, the notion of recording a supervisor for a given date as one who hasn't been hired yet doesn't make sense.