Cannot retrieve Manager ID

Summary:

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Hello experts,

I've created the attached value sets retrieving the employee Manager ID.

If I launch the query it retrieves the manager id correctly while if I launch the FF it doesn't return any values.

What could it depend on?

Below the FF configured

L_ASG_ID = get_context(HR_ASSIGNMENT_ID, -1)
RETURN_VALUE=' '
L_ASG_ID_char=TO_CHAR(L_ASG_ID)
/*RETURN_VALUE= GET_VALUE_SET('ST_PAR_MAN_ID','|=PERSON_ID='''||L_ASG_ID||''''||'|EFF_DATE='''||l_effective_date1||'''') */