How do you have demand for a Planning Method K part?  It must be appearing on an order or requisition somewhere, yes?  Is it possible that someone is changing the planning method temporarily to something else to fulfill or create a shop order, but forgetting to change it back before MRP runs?  The only way to tell this for sure would be to enable the history log on the Inventory Part > Planning Method.

Hi,

Thank you for your answer, I am sure that the planning method on the inventory part has not been changed, but can it be overriden somehow?

When investigating further I found two scenarios.

The first is when the K-planned part is needed by a P-planned part that at the occation has 1 pcs in stock. all demands for the P-planned part is then shown in IPAP and broken down to the K-planned part and it’s components. On the P and K-planned levels, no supplies are shown. 

The second scenario is when the K-planned part is included in a product structure for a part that is DOP-controlled. Also here demand seems to be correct on the component level.

Since demand is correct on components in both scenarios I am considering just to ignore the Exception messages. Do you think that would be a risk?

Since you can trace the reasons the item appear in IPAP to two specific scenarios where the demand is coming from a known source, but the supply is from an unusual source, then yes, I think you could be safe in ignoring the Exception message in these two circumstances.  It is good to have the investigation and understanding though.