In my PDI I did this as a Dictionary Override on the Short description field for the Incident table, so that it wouldn't apply to every task table, but you can do it either way:

To confirm, view an Incident record and see that the Short description is shown in the header instead of INC0000xx:

To test the slushbucket, I added a List Collector type variable to a Catalog Item, with the List table being Incident:

Where is the slushbucket that you are not seeing the new Display field?