Proxy setting for knife ssl check

I have set up a cloud chef instance and the knife ssl check command fails. I added the settings http_proxy, http_proxy_user, http_proxy_password, https_proxy, https_proxy_user and https_proxy_password to the knife.rb file but it doesn't resolve the issue. Is there a known fix for this?
Here is the error.

PS C:\Users\xxxxxx\learn-chef> knife ssl check
Connecting to host
ERROR: ArgumentError: unknown proxy scheme `https'

I am running this on a Windows machine. Also I found this post but it didn't help.

Thanks for the help in advance.