It shouldn't have anything to do with the iAds setting, but you do need to make sure Settings > Privacy > Location Services is ON and that OmniFocus shows up in that list and switched to ON.
(Also, if you're looking for a guaranteed, usually prompt response, your best route is to email or call us: 800 315-6664 or +1 206-523-4152 or
omnifocus@omnigroup.com.)