Have the same problem 'Mary' mentioned and reported in her solution. Here's my story:
New contact system using 'Lists' needs major fixes. (1) My listing of contacts within a group are in no particular order. (2) Added/modified Contacts in a list. Checked my work when done and list was fine with additions and one contact whose email was changed. (3) Several days later I used the list and the modified contact was not in the list but, surprisingly, when I sent the email it went to the contact but using the old, erroneous email address! The contact is nowhere in the 'All' list with the old email address.
What a job it is now to put a contact into several groups! I rely on groups for many reasons. Are Mary and myself the only users with such problems?