It's kind of a long explanation, but we'll start with looking at wolves. As you know, dogs are pretty much long-domesticated wolves. Wolves will rarely attack their prey unless the prey runs.
It's just the way they attack, and they evolved to do this because it just worked a little better, so they adapted to make a retreat attack even better. The reason it works better is because if an animal is facing you, only focus on you, when you are trying to kill it, your chances of becoming injured are much greater than if the animal is facing away and busy running. And wolves are fast enough and have sharp enough teeth to take that prey don't just fine even if it's running. So they evolved and adapted to hone that sort of attack. Also, if that animal is too sick to run, it might make you sick if you eat it.
So now running ignites their prey drive. They often will eventually just decide not to go after a even a perfectly viable prey option if the animal can keep calm and keep from running, even when the wolves goad it. That's why if you see wolves on TV with a pack of prey, you'll probably be wondering wtf is wrong with the herd, as they're just standing there. That's why.
But the dogs almost certain know you aren't prey. But their instincts still tell them don't get in a direct fight, and their instincts also make them feel like they should chase and try to catch anything that runs. And, if you aren't afraid enough to run, well that means you don't think they are a threat, and if you believe that, they think you just might be right.
Good job on knowing not to run. Oh, and don't make eye contact either, just so you know. That is a challenge.