Created Unassigned: SharePoint List Destination Error w/Visual Studio 2010 [20223]

I have an SSIS package that works with, among other things, a SharePoint list, both as a source to create a SQL Server table, and as a destination to update two calculated columns. This process was originally designed with Visual Studio 2008 and SQL Server 2008, and has been running in a productive environment for several months.

Lately, we migrated to SQL Server 2012, and most of us still have Visual Studio 2010, since SSIS was originally not available in VS 2012. I am attempting to convert this package to Visual Studio 2010, and running into an issue with the SharePoint List Destination. The Source adapter seems to work fine. I have the 2012 version (beta) of the adapters installed.

The problem is, in Visual Studio, when I edit the SharePoint List Destination task, have all the properties set as before (and as the Source properties are set), clicking on the Refresh button causes this error:
___System.InvalidOperationException: Sequence contains more than one element at System.Linq.Enumerable.SingleOrDefault[TSource](IEnumerable1 source) at Microsoft.Samples.SqlServer.SSIS.SharePointListAdapters.SharePointListDestination.CreateExternalMetaDataColumns . . . etc.___

Full error is attached . . . as a result, the correct columns are not listed in the Column Mappings tab, particularly the ones I need to update.

Larry