Hi there. I Think I had the same problem you have (but with jBPM 5.2). I used to following workaround:
ksession = JPAKnowledgeService.loadStatefulKnowledgeSession(sessionId, kbase, config, env );
registerWorkItemHandlersAndEventListeners();
initPersistenceLogger();
if(workitemId != -1){
WorkItemManager wManager = ksession.getWorkItemManager();
wManager.completeWorkItem(workitemId,null);
}
So i had to store the sessionId and the actual workItemId.