When using the "Transition Date/Time Field" along with the "@TransitionName" parameter the indexer will throw an exception if the transition name is not found in any of the workflows.
The exception given is:
This seems to be caused by an empty "actionsIDs" collection being passed to workflowHistoryDAO.findWorkflowEntry(issue, actionIDs);
This line checks if the collection is null but does not check if it is empty:
Normally if an error occurs, null is returned instead of the collection, however, in the case of an invalid workflow transition name, the collection is created but never filled. This can be seen here: