Raised a purchase order (PO) for a quote, however when I run MRP it includes these purchase orders for quotes, as if stock is due in on PO. How do I get MRP to ignore certain PO order types?
This can't be done on an order type basis. You would need to push the due dates way out on the PO or use revisions of part codes which are set to ignore in MRP.
MRP will start the PO raising process using what ever is set under that user. It can then change the purchase order type on the first screen. Please check user permissions; which security profile they are added to (system, user records, security profiles). Also check the Supplier Record: