Wordpress Custom Login Form in Header

I am trying to implement a custom login form in my theme header, but something is causing the login to redirect with a dump to the querystring with no login action.

Here is the test site url: http://tranmer.ca/TEST/ready4rent/

Have tested all of the plugins (on/off) and they do not seem to be impeding the login. When I changed the theme, it did work fine, so I suspect it is something in the theme. header.php seems ok, so likely something missing from functions.php? Any thoughts or help in the right direction would be appreciated.

I have tried a plugin implementation via UserInfoLoginShortcode as well as the custom code that is in there now, and both produce the same result.