I recently wrote a WCF service as a wrapper over CRM 2011 online and hosted it in Azure. The intent was to use this WCF service as BCS connection to integrate CRM 2011 online with SharePonit 2013 online. I tested the service with WCF Test Client and it was working fine.
The next step was to create an External Content Type in SharePoint Designer 2013. On selecting the External Content Types link inside SharePoint designer I kept getting the below error.
Next I used SharePoint Designer 2010 to connect to the SharePoint 2013 online site. There it didn’t throw the Metadata Store is currently available error.
However I kept getting the following error while trying to create a new external content type.
The workaround was to connect to SharePoint 2010 online site through SharePoint Designer 2010 and then generating the BCS Model from therein using our Azure Hosted WCF Service.
Hope it helps.