The reason MWI is not working is because Google has no interest in the OBi device, otherwise it would be working. I am in no way defaming them in their own house. I think Obihai is just not being clear with what "Official" support means which could confuse certain customers.
"To be clear about the term "supported", there are two different ways to look at the term: "we allow access to something we control" or "we provide technical or development support for you to do something we control." In the case of Obihai, it's only the former definition.
Historical background: Obihai was formerly using an unauthorized, unapproved method to access Google users' accounts to use the Google Chat (XMPP) protocol for calling, etc. This method was turning over the Google user's user ID and password to the third party -- a security exposure. Google did not approve of (or "support") that access.
Google has a safer method of controlling access to its users' account data and services, via a secure authentication method known as OAUTH 2.0. Google "supports" the use of that method to authenticate (verify permission) to use their customers' accounts, and the user controls which services to which the third party is given access. "Support" means, Google publishes the method and makes it available for use by others. Obihai converted their device firmware to use this supported authentication method. Google is not supplying any "support" to actually make use of the data or services accessed.
After Obihai upgraded their products to use OAUTH 2.0 authentication, Google said, in effect, "we agree that you are using a supported method to access our users' accounts". That's all. The rest is up to Obihai."
http://goo.gl/ooH7tE