My contact groups worked OK yesterday but then I installed the WLM update*.  Today my contact groups no longer work in Mail.  They are still correct in Contacts; when I click 'To' and start typing, the group is recognised and enters, formatted as normal, into the 'To' panel.  However when I try to send, WLM can't find any contacts.  Right clicking on the Group name and 'Edit' would previously show the contacts but the group is empty.  This in spite of the fact that in 'Contacts' they're all present and correct in their group.

Unsure whether this was a bug or an installation problem I ran Repair (Control Panel>Programs and Features>Windows Essentials 2012>Repair) and it reported a successful repair but I still have the problem.  Is this a newly created bug?

*WLM 2012 (Build 16.4.3528.0331)

Windows 7 SP1 64 bit