Hey David,
I’ve double-checked the latest version of Kanso, and the mentioned option does have an effect on the number of portfolio items on a one-page layout; I would be very grateful if you could tell me which version of Kanso you are using (you can find this information on the first page of the theme manual), and which settings you’ve tried in the “Number of portfolio projects per page” field in the “One-Page Website” tab of the Theme Options panel. Thank you!
Sincerely,
Andrii / Satori Studio