Organizing and accessing contact information in Outlook.com
I have the same problem as well. Everything was going right (had been forwarding documents or email to some of my groups) and BANG... they magically suddenly disappeared. Have we found an answer to this problem yet?
I did what someone else did... the day after it occured. I simply took a few recent emails I had sent (in both French and English) and copied the list of recepients (which appear in my BCC ... that's how I send notes to groups) from my copies in my Sent folder... and pasted the results of the Copy in news groups (which I gave the names of the old ones). Problem solved in terms of my use of groups... but obviously, this is a major problem for Microsoft to resolve for the whole community.