[horde] Problem adding and deleting group members after Webmail 1.2.9 upgrade

[Mail Room]

We have experienced a problem after upgrading from Horde Groupware 
Webmail Edition 1.2.9 from 1.2.8

We can no longer add or delete group members.  No error is reported on 
the screen - it just says that update was successful.  When going back 
to the group the deleted entry remains or the added member is missing.

Any ideas?