When you released a purchase order from a purchase agreement with the max is enforced slider to yes, the PO is automatically link to the related purchase agreement. If you modify the quantity, the link is then broken with the purchase agreement. If you re-modify the quanitty and bring it within the allowed quantity, the link is recreated and the purchase agreement is reattached to the PO. But, once the link is broken, the fulfillment is not updating anymore even tough the purchase agreement and the PO are connected to one another.

The idea is that the link needs to be recreated and the update has to be there. Now, if you broke the link and reattached it, the updates are not happening. That causes problem because the contract you have with the vendor is not updating and so is not true anymore. It needs to keep updating so the contract stays relevant.