Multiple value custom field group fields in Views

Problem/Motivation

CiviCRM multi-valued custom field group Views integration broken

Similar to https://www.drupal.org/project/civicrm_entity/issues/3312320 →
https://github.com/eileenmcnaughton/civicrm_entity/issues/370

Steps to reproduce

Create a new custom field group in CiviCRM, for contacts. Check the "multiple values" checkbox.
Create a custom field in the group.
Add two records for this new custom field group on a contact
Now make a View listing contacts, add this field to the View. Also add "Display name" field

No values for either field are rendered by Views. The number of rows is correct. Happens whether field values are rendered in one row, one row per value.

Proposed resolution

Fix the bug