Hibernate update is sometimes not working

I have a requirement where I am updating rows according to uuid's where one uuid may be associated to more than one rows.

Here's the scenario: 4a90558c-4a5b-4af7-8c68-60ff81f74ef3 is my uuid and it exists in 8 columns in my DB.

and my java code is as follows:

    try{
        session = sessionFactory.getCurrentSession();
        tx = session.getTransaction();
        criteria = session.createCriteria(Archive.class);
        criteria.add(Restrictions.eq("bagUuid",  "4a90558c-4a5b-4af7-8c68-60ff81f74ef3"));
        ScrollableResults items = criteria.scroll();

         while ( items.next() ) {
             Archive archive = (Archive)items.get(0);
             archive.setDecision(1);
             archive.setOperatorAssigned("test");
             session.saveOrUpdate(archive);
             session.flush();
             session.clear();
         }
         tx.commit();
        LOGGER.info("Archive Record is updated: "+archive.getFilePath());
    }catch(Exception e){
        recordUpdated = false;
        tx.rollback();
        LOGGER.error("Archive Record failed to update due to exception in updateArchiveRecord method: "+e.getMessage());
    }

Here sometimes all records associated to UUID is updating but sometimes failing. I think it may be a issue with the Hibernate API. Does anybody else has faced the same issue.