Current month's forecast is not being considered in the MRP calculation

I have done some regression testing for the -999 planning fence setting, but it is not functioning as expected.

For the some parts , I changed the planning fence to -999. The calculations in Supply and Demand appear correct after rerunning the MRP. However, the MRP messages are no longer taking the current month's forecast into account.

As a result, at the end of each month, the MRP projected balance is short by an amount equivalent to that month's forecast quantity.

Why the current month's forecast is not being considered in the MRP calculations?

Best Regards,

Kedar