Free/Busy Error from Exchange Online Cloud Mailbox to on-premise

Hi, have a successful federation configured between Exchange 2010 SP3 (latest Roll up) and Office 365. This is to allow free/busy lookups during various migration stages (this is not Exchange Hybrid). Autodiscover works well and all functions work ok.

On-premise users can see cloud users free/busy

Cloud users cannot see on-premise users free/busy.

All local based free/busy works on-premise and in the cloud.

The Exchange Connectivity tool returns the below error from all accounts, this is the only error:

(A wildcard certificate is in use and am wondering if this could be contributing to the problem as I have seen this once before)

	Attempting to send an Autodiscover POST request to potential Autodiscover URLs.
	Autodiscover settings weren't obtained when the Autodiscover POST request was sent.
	Additional Details   Elapsed Time: 4979 ms.
	Test Steps   The Microsoft Connectivity Analyzer is attempting to retrieve an XML Autodiscover response from URLhttps://autodiscover.company.com/AutoDiscover/AutoDiscover.xml for usertr3@company.com.   The Microsoft Connectivity Analyzer failed to obtain an Autodiscover XML response.   Additional Details   An HTTP 401 Unauthorized response was received from the remote Unknown server. This is usually the result of an incorrect username or password. If you are attempting to log onto an Office 365 service, ensure you are using your full User Principal Name (UPN). HTTP Response Headers: Content-Type: text/html Server: Microsoft-IIS/7.5 WWW-Authenticate: Negotiate,NTLM,Basic realm="autodiscover.company.com" X-Powered-By: ASP.NET Date: Sun, 15 Jun 2014 22:33:34 GMT Content-Length: 58 Cache-Control: proxy-revalidate Proxy-Connection: Keep-Alive Connection: Keep-Alive Proxy-support: Session-based-authentication Elapsed Time: 4979 ms.

Any help or guidance would be appreciated as this is the only error we receive now and everything else works.

Kind Regards, Antonio.