Steps to reproduce:
1. In a 3.x build, publish an event with a workflow which contains two publish-engage operations. Make sure that the published event is playable via player of your choice.
2. upgrade 3.x to 4.x using the process described in https://docs.opencast.org/r/4.x/admin/upgrade/
3. Complete the reindexing (recreateIndex endpoint).
Events which were subject to the workflows with double publish-engage operations are not searchable via the /search endpoint.
Events subject to a workflow with a double publish-engage operations should be searchable after migration just as they are searchable prior to migration.
Workaround (if any):
Delete solr-indexes, 'null'-ify deletion_date record in mh_search table for relevant events and recreate indexes.
See PublishEngageWorkflowOperationHandler.java:760 and SearchServiceImpl.java:435. In the least, the second publication should remove the deletion_date from the event in the mh_search table.