Multi-record custom fields on a Tab does not always show all values

How to reproduce:

• create a custom group of type "Tab" that can be "multiple", for Contact records, with two fields.
• edit a contact record, enter 3 set of values, save record
• click "edit" to modify the custom values: sometimes it will display only 1 value, sometimes 2, sometimes 3.

CiviCRM does seem to fetch the data for the custom values (we can see the http requests), but not display.

http://drupal.demo.civicrm.org/civicrm/contact/view/cd/edit?tableId=202&cid=202&groupID=6&action=update&reset=1