Sitecore WFFM Error on 8.1 update 2

On Sitecore 8.1 CD server after using the supplied SwitchMasterToWeb.config and having installed Web Forms For Marketers 8.1 rev 160304 - I get the following error when trying to access a form:

Unable to cast object of type 'System.String' to type 'Sitecore.Analytics.Reporting.ReportDataProvider'

The error occurs because Sitecore is trying to connect to the master Db and is getting a failure because it is not accessible. I suspect that SQL is returning a string error message instead of the expected object.

If you open up the SwitchMasterToWeb.config and comment out the following block it will resolve the issue:

<reporting>
  <dataprovider>
 <datasources>
   <add key="collection">
  <filtersfactory>
    <param desc="definitionDatabaseName" />web
  </filtersfactory>
   </add>
   <add key="reporting">
  <filtersfactory>
    <param desc="definitionDatabaseName" />web
  </filtersfactory>
   </add>
 </datasources>
  </dataprovider>
</reporting>