Trying to identify Contacts with a Property Value but not associated to related Custom Object

@VPathania I was not referring to the “Associated records” dropdown. List 1 would be created as follows:

  1. Create contact list
  2. Click ‘Add filter’
  3. Change ‘Filtering on’ dropdown from Contact to whatever your custom object ist
  4. Pick any property that is available on any record, e.g. “Create date is known”
  5. Save list

Best regards