Hi @Vlad Gromov
According to our research, you may have accidentally hidden the contact in some operations.
According to the document: If you want to hide a contact from your suggestion list, it is possible to do so in the contact suggestion list while addressing an email. This can be used for personal contacts, contacts we have discovered on your communications, and contacts in your organization (as applicable). Contacts hidden this way will not be returned as suggested contacts in Microsoft 365 products (e.g. Outlook, Teams, etc.)
If you want to un-hide a contact, send an email to the contact by replying to an old mail or by typing the full email address on a new mail. After approximately 24 hours, the contact will be unhidden from the suggestion list.
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