Why does "compose" no longer present choices from contacts?

Last week when I clicked "compose" and typed the name of a group whose members reside in "contacts" the names appeared on the address line for my proposed message. Now they don't. When I type an individual's name I get it in a red bubble that I can't use to send my message. I have to hunt up and type in the e-mail address of that individual by hand in order to send my message. I hope to restore the function that used to present a list of choices for my message recipients.