To display Custom User fields through Profile Publish Access, perform the following (requires the Platform Manager role):
  1. Navigate to Core > Settings
  2. Select Profile
  3. Click Profile Publish Access
  4. From the dropdown, select Student
  5. Under Manage Publish Fields, click Student to Parent
  6. Click the Edit button
  7. Mark the desired checkbox(es) under Custom User Fields 
  8. Click Save & Confirm
  9. Review and click Confirm