When workflow has “wait” step, it’s backgrounded and a workItem is created with expiration time. So until that time passes, that workflow will not restart. Once it’s time you need Perform Maintenance task to run to pick up the workItem and progress the workflow.
If there are errors (and I’ve seen it happen) the workItem can get locked and workflow does not get progressed. In such case delete the lock in debug and it will work again.
If it happens frequently you might want to look in to the correctness of your workflow.
Also just to be clear: event starts a workflow and that creates task result. If you have no workflowCaseId in your task result it could mean it’s finished or died on error.
You mentioned that task has been stuck for days? What exactly do you mean by that?