Summary:Users on tenant are unable to access Nintex forms. The users get the following error: 'Could not authenticate with SharePoint. Please close the browser and try again. If the problem persists, make sure Nintex Forms Online is installed properly.'
Product:Forms for Office 365
Symptom:Not able to open form and get an error
Cause:Item-Level Security has been set to none for create/edit option.
If you get this error, try switching the Item-level security to allow users to create/edit their own items and the form should work.