John
First things first. You have a 6 month old vizsla puppy. He's not an adult dog yet. You're going to have inconsistent behavior and results. It's just the nature of a dog that age.
I'm not an advocate of pinch collars, or choke chains. In the hands of an experienced handler they are an effective aid. In inexperienced hands the results can border on cruel if not used properly. The same with eCollars. Very effective tools, but they too can be abusive if used improperly.
Any aid, pinch collar, choke collar, or eCollar, is an "extension of the leash" They are not the primary training device. Once a behavior is established these device allow the handler to "extend the leash" by using the principles of re-enforcement. The key is that the command, or behavior has to already be taught.
Vizsla's can be tough because of their energy levels, some would call it hyper, but they are a very biddable, soft dog by nature. They are highly intelligent, and pick up things so quickly that as owners we a lulled into a false level of confidence in them and our abilities. We think they are rock solid because they pick up a command so quickly, but the component that is lacking is the time required to make that behavior a patterned response. It's very easy to suspend the training of a command because they appear to get it so qiuckly, we believe we are done with that.
The heel can be tough. I know that people erroneously believe it to be one of the easier commands, but is isn't. The heel is control, and it is a command that really needs to be instilled. It is what keeps a dog safe and under control.
If a dog comes when called, and heels properly it's almost enough by themselves if the dog learns no other commands.
The end result is that the dog should heel naturally without command or use of a leash, and be commanded to move off, or released from the heel without a leash.
Put them on a 9'-12' leash and keep a loop in your off hand. when they begin to pull on the leash, or move in a direction you aren't, drop the loop and immediately change direction, 90-180 degrees. Don't pull or yank on the leash. Drop the loop , change direction and keep walking at an even pace. They will be momentarily off balance from the release of the pressure when you drop the loop, and will have to move in the new direction to regain their balance. Keep a loop in your hand and change direction every time they exerts pressure on the leash. When they yield and changes direction walk backward encouraging them. Give them the come command and kneel and praise them. There has to be reward
Each time you change direction give them a short whistle cue. I use two quick whistles when I change direction. It means to the dog, Pay Attention to me! It's not the "Come here" whistle, it's one where I want there attention on me. When you change direction in the woods grouse hunting, this is the same signal you will want to give them to move in the same direction as you are, even though you may be a couple hundred feet apart. All of my Vizsla's have been very communicative. I communicate with them constantly during training and hunting, either by voice, whistle, clap, or slap on the thigh.
I like to use the longer lead, 9'-12'. I keep a section of the lead in my left hand ,and have the remainder sort of loosely looped in my right hand. There is enough lead in my right hand though to twirl the excess lead in front of my dogs nose. If they start to move forward they get a little"bip" under the jaw. Nothing harsh just the weight of the lead.
When you do the heel to the left, expect that they won't pay attention. You are going to purposely run into them with your knee, once again no rough stuff like purposely kneeing them. You are just going to "walk through them" and keep going. It's very planned. Work them in a "square" to the left a few times and then the right. Eventually you put everything to together in a random sequence.
At some point they will just sit down, or refuse to move. They are confused now,and don't know what to do. When this happens take a Big Step back on their training. Talk to them, soothe them, and then gently move them off in a straight line at the heel. They're done for this session. finish on a positive.
It's amazing how similar walking a dog at the heel is, to walking a horse at lead. The training is pretty similar also. The horse is just 7' tall.
I personally do not use treats during training. If a person wants to though, it's their dog not mine, so it's a personal decision that is theirs. I do use treats to test the dog to see whether or not it is "playing dumb" with me, and trying to take advantage of me. I've caught mine at it from time to time through the years.