The DC catalog for events in mh_scheduled_event from OC 3.x systems includes an identifier in the DC catalog that is the numeric event ID rather than the mediapackage ID, e.g.
This is kept in the event DC catalog during the migration process, although this identifier is no longer in use. When the event is provided to the CA in an ical calendar after migration, this identifier is still there in episode.xml and causes problems for Galicaster and possibly other CAs.
Solution is to remove this attribute during migration.
8175713, Remove event id from episode DC catalog when migrating scheduled events #33