AX2009 Dimension question / problem

I have a problem in which an item is showing up in a work order without a InventLocationId (warehouse to us). Looking at the UPDATE tab on the production order shows the part belonging to dimension no: AX#422. Looking at field InventDimId in table InventDim shows no value for this dimension in the InventLocationId field, but a value in the InventSiteId field.

Looking at a comparison part in table InventDim, the InventSiteId & the InventLocationId is filled in.

Both parts belong to the same dimension group (DEF). Looking at shows
that site and warehouse are active but warehouse is not mandatory.

Looking at the error item in it displays the item as belonging to dimension group ID000000468.

The part is type item, not configurable or modeling-enabled and looks like another part which fills in the site and warehouse correctly on the work order.

Does anyone have an idea why the item’s warehouse goes missing on the production order based on the above?