Job Summary and Invoice Summary are treated as two unique items. The office compiles the Job Summary for the technician prior to the technician going out. Then the technician creates an Invoice Summary (which the client see's on their emailed/printed invoice) on what the technician found or completed while on-site. An office person can edit/add to the Invoice Summary if needed before or after the technician goes out to the job. Hopefully that helps.
It only appears if the technician puts something in the invoice summary. Soon this will be required with the new update.