Repro steps:

• Have an Entity with a lazy loaded list
• Load the Entity in a transaction and initialize the list
• Close transaction and save the reference to detached object
• Merge the object in a new transaction and do not touch the collection
• OrderColumn will be updated after commit of second transaction

I belive the problem is in OneToManyPersister and org.hibernate.collection.internal.PersistentList.Clear (Persister seems to shift items when a clear operation is queued)