IN SWM module, Does R1775 always creates Line in F4812 for Billable Flag Y.

IN Service Warranty Management module, R1775 is creating Line in F4812 for Billable Flag Y with Actual Quantity =1, Estimated Billable =50 but Actual Billable amount is zero and Percentage covered is 0.00 for Line Type N. Is this working correctly as standard expected behavior.? Observed for Line Type J, Actual Quantity if kept blank, Estimated Billable =50 but Actual Billable amount is zero and Percentage covered is 0.00, it does not create record in F4812. Is this working correctly as standard expected behavior.?

Why I see such different behavior in both case. Can someone explain if Actual Quantity or Line Type is driving factor behind such different behavior.