"Remove from undefined" button title when removing user from group

Login to Nuxeo Server as an administrator
Go to WebUI admin tools, Users & Groups
Search for Administrators group
i.e. /nuxeo/ui/#!/admin/user-group-management/group/administrators
Hover mouse over the X icon on right, as if to remove user from group
See title/tooltip with text "Remove from undefined" - this should be "Remove from group" or "Remove from Administrators group" or something relevant.

The html source is:
<paper-icon-button icon="nuxeo:clear" noink="" title="Remove from undefined" role="button" tabindex="0" aria-disabled="false">