This is because you are using the Inquiry_Name placeholder which pulls from Person Inquiring
on the inquiry form (so if you are not using this field on your form it will be blank when the notification is sent out)

If you are using the Student_Name placeholder pulls the First Name, Last Name from the Inquiry Form.
To check to see which place holder you are using, navigate to:
  1. onBoard
  2. Settings
  3. Inquiry Forms
  4. Click Settings on the Form in question
  5. Select the Confirmation Notification Tab
In the E-Mail Body: you can see which place holders are being used by the brackets for example [inquiry_name] 

The fields being used are all located in the Applicant section on the Inquiry form.

To check which fields you are using, navigate to:
  1. onBoard
  2. Settings
  3. Inquiry Forms
  4. Click Form (icon with the editing pencil and the word Form) on the Form you want to check to see which Applicant Fields are in use
Look for Person Inquiring (If  Required- No and Hide are highlighted in red then this is not being used) therefore the Inquiry_Name placeholder will return as a blank result.