re: "Progress of work (code) is not very clear until complete."
That is incorrect. The progress of the code is very clear and very demonstrable with each completed milestone.
If not, then you need to hire a different project manager.
I am a developer. Clients can see the progress and completeness of every step. They can test it out for themselves. There is no such thing as waiting "until the project is complete." As far as I am concerned, the only freelancers who work that way are scammers.
re: "Freelancer wants payment released with every milestone."
That is correct.
re: "I am giving them some space and have released two payments."
That is fine. Just so long as you understand that once you release an escrow payment for a milestone, you will never get that money back. No matter what. When you release payment, you are certifying that you approve of the work done for that milestone.
re: "However my concern is I do not want to release more payments until the code has passed our final checks at our end."
You need to release payments for each and every milestone.
If you are not comfortable with that, then use hourly contracts.
It is theoretically possible to use a single contract for the entire project. Doing so is not prohibited by Upwork ToS. But that is a recipe for disaster from a project management perspective. No experienced client of development projects will suggest that you should try to stuff a entire project of significant scope into one all-or-nothing milestone. The path to success always is to create complex development projects in a modular fashion.
re: "Cannot evaluate ongoing code at the moment."
That is not correct. If this is how you feel, it means you working with the wrong developers and/or the wrong project manager.
re: "How do I handle milestone payments to ensure payment released only after all code is submitted and cleared at my end?"
This is not an option, aside from doing an all-in-one milestone, which is a recipe for disaster. You might as well not even try, as far as I'm concerned.
re: "How do I set it to release money after code has passed review."
This is not an option, aside from doing an all-in-one milestone, which is a recipe for disaster. You might as well not even try, as far as I'm concerned.
re: "What options do I have if final code is not what we required?"
Ofhers may discuss the answer to this question in more detail. But in my opinion, any "options" you learn about will be destructive to your efforts. Refund thinking hurts clients. You would be better off if you decide right now that no matter what, you will not try to get a refund or get money back from a freelancer. Thinking that there may be a safety valve is a huge gamble, and you could end up like many other clients who had refund thinking: losing unrecoverable money paid for unusable work.
Instead, do this: Monitor the work closely. Evaluate the work as you go along to make sure that you are getting what you need, with the level of quality that you require. If any freelancer does not provide you with work that is of great value to you, then end their contract. Stop working with them. Assign their tasks to the other members of the team.
re: "I want to talk to chat support about this individual issue directly"
It is not Upwork's intention that you discuss this topic with Upwork Customer Support personnel. You will receive far more in-depth information here in the Forum. You certainly don't need to rely on my opinions only. Feel fee per to read other threads. Feel free to ask other questions. Feel free to wait until other experienced Upwork users provide their advice to you. My notes on this topic represent the ideas of just one person. I don't work for Upwork. Upwork employees are not going to be able to provide you with advice that represents diverse viewpoints such as the perspectives of clients, freelancers and developers.
