There are many reasons behind this Emails disappear from Inbox Outlook problem is that your account has been compromised and someone else is accessing it. It is required to check the email accounts of all users when you have a pop3 server. If you are not connected, you should be able to open and read them. Otherwise, the emails will disappear from your inbox. You can use search folders to organize emails that have already disappeared from your outlook inbox.
For more read, you can go with this blog - https://emailscrunch.hpage.com/method-to-recover-emails-disappearing-from-outlook-365.html
For more read, you can go with this blog - https://emailscrunch.hpage.com/method-to-recover-emails-disappearing-from-outlook-365.html