I had the same issue, tried all of the steps detailed in the answered posted here and was on the phone with Customer service for over an hour. They had me do the same steps and of course could still not get the service date to print on the invoice. When I created a new "company", because our company is branching off into a new area I found that the service date was appearing. When I started comparing the template from each company I found that the "Show more activity options" had the "Group activity by" field set to "Day". When I turned that off. the Service Date was displayed on the invoice. This is definitely something to check into and would also be a good thing to have the customer service reps check with a customer who calls in with this issue. It is sad that this was a problem for so many people for years without having a resolution.