Access Denied Error When Saving Workflow Templates Or Snippets

Summary

When trying to save a workflow template or snippet, with a user account that has both "Full Control" permissions at the web level and is a member of the "Allowed Workflow Designers" list, an Access Denied error might occur.

Solution

Grant desired user accounts "Contribute rights" to the hidden library at the site collection level. The library is located at YourSiteURL/NintexTemplates.