Wow! Unusual in a Basenji…....they are usually really happy to earn food. My BC wouldn't even look at food if there was anything else of interest around. Fortunately, like most Border Collies, he would work his heart out for my approval.
It is possible to get around this problem. I would suggest learning a little bit about clicker training, then work with him at home, free of distractions. Make sure your rewards are particularly yummy. (Food is the best answer here, simply because it is quick. Playing with toys, etc, takes too much time and interrupts the flow of training) Many dogs get into the "game" of figuring out what will earn them a reward. Eventually the click itself becomes positive reinforcement, a la "I got it!". Hopefully he will get into the spirit of it, and then you can begin challenging him a bit more. I would suggest putting "watch me" on cue. Practice a lot. Then try to make it a behavior you require when he sees another dog, to the point where seeing another dog becomes the cue.