Elsa 2.8 Cron expression not consistently starting workflow

I have created a workflow using the designer and scheduled it to run every hour. It runs for the the first one or 2 hours successfully then doesn't run anymore. It will however run again for a few times if I change the cron expression and publish but that will eventually stop running aswell. I've attempted changing the expression to run at minute intervals and it runs for a while and eventually stops aswell. I am not sure why it does not continually run at the expected interval