I have the same issue. A number of emails sent to my Outlook id haven't reached me. Once I came to know about it, I called the senders and asked them to send a copy to another email address of mine while sending it through Outlook.com.  I did receive the copied ones from the other server, but the emails to Outlook.com did not come through. It only occurs for a few emails, and I continue to get emails throughout the day (except a few missing ones). The emails did not go to the spam or junk mail folder either. 

I would appreciate it someone from Microsoft could help me with as these are important emails.

Thank you