Yes, in basic mode the dropdown should show all the available Data Sources.
When configuring the MongoDB Query component, set the properties starting at the top of the list and working downwards. For example:
Basic/Advanced Mode = Basic
Server = the IP address of your MongoDB server
Database = the name of the database you’re trying to access
If the Server or Database are not correct, or if there is a network problem preventing Matillion from accessing the MongoDB database, the Status will confusingly still show as “OK” for those properties. Only when you open the Data Source property you’ll find the dropdown list is empty.
Are you certain that the Server and Database names are correct, and that Matillion has network access to the MongoDB server on port 27017?