Connection is not established when url redirecting

[Knskan3]

What Is the issue?

when creating a new iframe new Postmate( if the URL is given redirects, i.e 301 to add www. to the domain, the connection with the child won't be established.
Tried both with and without redirection on the same (basically using a domain without www. which automatically adds it).
It only works when no redirection involved.

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