Good to hear things are going so well! Would suggest phasing out the treats, rather than going 'cold turkey'. Would suggest moving to randomly food rewarding the behavior - rewarding the first, then third, etc. correct response before moving to the occassional food reward or phasing out all together. It takes an immense amount of practice (repetition) and rewarding for a behavior to become habit, especially behaviors that are 'difficult' for them, and intermittently rewarding keeps them 'in the game', (like people playing slot machines) and I am always prepared to offer a high value food reward for those mind boggling, 'Wow that was amazing!', moments.
Anytime I step out with Walnut, I fill up a treat bag with the home made liver bits. We also use liver for classes, and able to get his attention with 3-4 dogs in the same room.
By the way - he's still responding really well to home cooked liver and his focus is 10x better! I'm able to walk passed other dogs, people, bikes, etc in daytime and nighttime with no issues. There is zero pausing, freezing, or anything.
Occasionally something might grab his attention for for 8-10 seconds, which I think is acceptable. Plus, if I say this name, or "let's go", he quickly "releases" focus from whatever has got his attention (usually something I can't see...kind of creepy), and carries on walking. It's those times where I give a nice size piece of liver.
Overall, he's doing so much better.