Symptoms

Created a simple workflow and it does not start except manually. Will not start when item is uploaded or changed like it should. This is urgent as it is holding up our development process and I am on vacation next week so I need to get this resolved.
 

Diagnoses

Using SharePoint Manager, we found that the URL for the Event Receiver is pointing to Test environment. As a test, we created a new workflow via K2 for SharePoint Designer on a new list, but still getting the same issue.
 

Resolution

It turned out that the default environment library was set to Development K2 Workspace > Management Console > Environment Library > Templates > Default Template > Environments. Setting the default environment to Production and redeploy the workflow, resolved the issue.