Although the traveler made their way home independently, you will still need to put in a second segment ‘home’ aka the last day of the business trip, to move forward.

If you look at the line item already created, 9/14 was selected for the departure and 9/18 as the arrival (Technically saying that your traveler was in the air for 3 days and didn’t arrive in Chicago until 9/18). You will need to first edit that segment so that the departure and arrival happened on the same day: 9/14, and then the ‘New Itinerary Stop’ will be the ‘return date’ aka end of business trip date to be 9/18 to make the second itinerary row that is required by the system: