Issue
The conditional criteria, for a conditional start workflow are no longer visible from the workflow setting.
This occurs after the Workflow designer is reopened, after modifying the conditional criteria.
This occurs after the Workflow designer is reopened, after modifying the conditional criteria.
Resolution
The issue has been fixed on the latest version of Nintex Workflow for Office 365 Apps that was released on 21th November 2018. Make sure that the site has the latest version of Nintex Apps