Saved Search Email Notification > Updated Fields > Inventory Location not showing

I'm using a saved transaction search to create a list of all sales orders with their respective locations and inventory locations. The location shows where the order originated and the inventory location shows where the order will ship from. As we use cross-subsidiary fulfillments, we need to use this Inventory Location. The report is fine however I would like it to email me if the Inventory Location is left blank or if it is different than the Location field. I went to Email under the search setup and then the 'Updated Fields' tab and looked for the field 'Inventory Location'.