Why there is no employee available under 'Add Subordinate' function in Employee Hierarchy?

Why there is no employee available under 'Add Subordinate' function in Employee Hierarchy?

Symptoms:

The hierarchy does not contain any employee list (not assigned to any manager yet) while the Admin attempt to “Add Subordinate” under Personnel -> Employee Record -> Employee Hierarchy.

Possible cause(s)

The employee to be added has not been granted “Access to Frontier e-HR”.

Suggested workaround / solution(s):

a. Go to Personnel -> Employee Record -> Employee Role
b. Select the employee and ensure that "Access to Frontier e-HR" has been granted to this employee
c. Try to add the subordinate in the Hierarchy again