After selecting the option in a multicontrol list and clicking on the submit data button, ingestion fails saying that "" is not a valid selection. This happens when the control is required, not tested when control isn't required. A list selection was made at time of the error.
This was due to additional checking being added for the XML importer included in 2.0.0-beta. This has been corrected in SVN and will be included in the production release.