:observer.start / :observer_cli.start blocks execution

Dumb question but scoured the web/forum to no avail. It is probable that im shooting in the dark and hope for some enlightenment

1. Basically i am running my Phoenix server application off the command line in Windows - and I cannot help but wonder is there a way to fire :observer.start or :observer_cli.start using the command line only - AND without blocking further execution.

My commands are as follows mix run --no-halt --eval ":observer_cli.start" && mix phx.server but unfortunately when observer_cli starts - mix phx.server is never executed. The same occurs for :observer.start.

2. Even if i run it off iex - using iex -S mix phx.server and subsequently running :observer.start i realize that executing the server off iex is much slower than the cmd line - by looking at the response times of the server to JSON requests. Is this normal? Or should it be the same?

Will love some advice how to study on how to use the :observer / observer_cli tools on a professional level.

3. Finally i realized one thing, when iex is running, it seems to intercept my endpoint responses and my tool, Postman never receives the server responses. It works only when i execute the server using the shell command. I think probably there is some misconfiguration somewhere - and will love any hints/advice.

Thanks.