We encounter a few user mails file having this issue.
Mails in the Inbox when missing but able to see the mail in All Document view. We try to update the index (crtl+shift+f9) but keep hanging at 95%. We try do new copy & replicated the mail file but still unable to see all the mail in the Inbox. We end up create a new mail file for the users.
What is the cause & how to resolve this issue?