Nav 2016 - Purchase order fully received and Invoice not deleted

Hi Folks -

One of our customer had a Purchase order with 2 G/L account lines and both these lines were fully received and invoiced

at one go, in other words they were not partially received or invoiced. After both these lines were received and invoiced the PO is still open and is not deleted. There is no customizations as such around this. 

This is the second time this has happened to this customer.

Does anyone know of any existing issue or is there any hotfix for this issue.

Any help is highly appreciated.