I'm trying to type an e-mail to a person whose contact info is in my Contacts
in Outlook. In the past, even if I had not sent an e-mail to this person
previously, I could type their name and Outlook would link it to my contacts
and allow me to send the e-mail. This is no longer happening.

In fact, when I click on the "To" button to select the contact/e-mail
address, it tell me i have an invalid ID (and not all contacts appear).

Could you please help me with this?