It is the Settings -> Reading page and the “Syndication feeds show the most recent” number that changes that Project -> Services display. I changed that value from 10 to 50 and all my projects under that service display as intended.
Thank you very much for your prompt response and great theme!
It is 10 items per Project -> Services page, not 12. Sorry.
I can edit the other characteristics of this page with taxonomy-corpo_services.php, but I still cannot get the page to display more than 10 projects under each service.