I am facing issue on binding or restricting people only field to AD group on Nintex form. User inserted in SharePoint group easily mapped to the field. When I add AD group in SharePoint group it did not show user Ad users while selecting user. By making field from people only field to people and group field, Ad group show on selection but it did not show user inside the AD group.
We required users inside the group to map with field on nintex form.
sharepoint is not capable of resolving members of AD group, it considers it as final security primitive.
so, AD groups are useful to setup access permissions for different SP's objects, but are of no use to backend people picker fields.