Question Fored Discharge not stopping at end time.

I am using an 18KPV inverter.  I am using FORCED DISCHARGE during the Peak tariff  period (2-6pm)of my local utility.

The inverter does not stop at the entered end time.

The only way I have found to stop the discharge is to add a charge period to book end the start and end times.  So my question is why does the end time not stop the FORCED DISCHARGE.  As a note, I am supplying power thru a back feed breaker to my main service panel to take some of the loads away from the grid supply.

Thanks for any help/insight.

Matt