When performing the wizard to materialization into a JDG data source, the nameInSource assigned to the JDG source tables is incorrect. Example:

CREATE FOREIGN TABLE Stock (
product_id integer OPTIONS(NAMEINSOURCE '"product_id"', NATIVE_TYPE 'integer', FIXED_LENGTH 'TRUE'),
symbol string(4000) OPTIONS(NAMEINSOURCE '"symbol"', NATIVE_TYPE 'string'),
price string(50) OPTIONS(NAMEINSOURCE '"price"', NATIVE_TYPE 'string', FIXED_LENGTH 'TRUE'),
company_name string(256) OPTIONS(NAMEINSOURCE '"company_name"', NATIVE_TYPE 'string'),
CONSTRAINT PK_prodid PRIMARY KEY(product_id)
) OPTIONS(NAMEINSOURCE '"Stocks"."Stock"', UPDATABLE 'TRUE')

The NAMEINSOURCE not be set or if it is, should be the same name as the table. In this case, "Stock".