Topic
Updating a Calendar item to All Day Event "Yes" using the Update Item action Is not supported in Nintex Workflow.
The Update Item Action can be used to update an event to "No".
Instructions
A calendar event can be created using the Create Item action which allows you to set the All Day event to Yes during the item creation.
Additional Information
If an event has a start and end time you cannot set an All Day event as its not all day if it has a start and end time.
