EF6.1.3 functionimport could not be found in the container

Using Entity Framework 6.1.3 (latest) my stored procedure (a function import) appears at design-time; disappears at runtime.
The function import appears to be present as Intellisense presents the function and its required parameters:
            using (var context = new eCRMEntities())
            {
                result = int.Parse(context.usp_GetIsMortgageEDILoanOwner(request.ID, request.LoanNumber.ToString());
            }
However, at runtime, this line throws: The FunctionImport 'usp_GetIsMortgageEDILoanOwner' could not be found in the container 'eCRMEntities' error.

I have removed and reinstalled EntityFramework from the solution - no change.
I have reviewed my connection string; the database connection is working.
I have other methods invoked on context tables (find() for example); they work just fine.