The contacts list has lost all the contacts.
The server is Outlook.com and the contacts are there.
As all your Outlook contacts are online and not locally, then you have 2 options to restore your contacts.
1). If you have automatic backups enabled in eM Client settings or do manual eM Client backups, then you can try restoring your last backup by date when you know the contacts where there. Click “Menu / File / Restore” and choose a restore date.
2). However if you don’t have any eM Client backups, then remove your Outlook account and re-add your account which will re-sync your Mail, Calendar and Contacts.
Note:- Once your Outlook contacts are back in eM Client, click “Menu / Backup” to make a backup.