Export fails with "Adding text to an XML document must not be null"

Trying to export data from a Bamboo instance we have been demoing on the embedded DB so we can try it on our Oracle instance. Export fails with the error "Adding text to an XML document must not be null" (looks like this is part of the AuthorMapper step). I believe the issue probably stems from the fact that one user that is referenced in the Bamboo DB no longer exists in LDAP.

I see no way to delete this user, as when trying to bring up the user in the user list you can no longer locate it. It does show up in the list of Authors, but clicking on the user name from that screen brings up the error "Unable to find the user. The username <uid> may be incorrect."

There needs to be either a way to proceed with the export or a way to cleanup the data so we can proceed.