I am using Nintex form and workflow to update SharePoint list item. First activity on workflow is "Assign a task". So as soon as I try to update SharePoint list item, Approver should get email for approval of the change.

My observation and problem is, approver not getting email when I am updating a SharePoint list item created by one user but approver getting email for approval, when I am updating a SharePoint list item created by other user.

At the same time, I am able to update any SharePoint list item using "Edit in grid view" option and this does not trigger a workflow at all.

I am a owner of SharePoint site, so I have all required access to add, update and delete item.