Payment is complete (check is cut) but encumbrance-Commitment is not cleared

I also posted this question in Payables Community because I am not sure where the issue happens.

In FY16 a requisition was made, then PO was created and finally the check was cut thru AP successfully.  However, the Amount still shows in Encumbrance-PO .

Any idea, what could have caused the above to happen?

Thanks for all the assistance!

DE