On the right side of the Inbox icon is a place where it shows the number of unread emails.
After going into my Inbox and reading all the unread email that shows there, sometimes the number to the right side of the Inbox icon still has some value, but in the Inbox, there are no more unread emails to read.
So I click on the Unread icon and it shows some unread emails there, the same number of emails as the value to the right side of the Inbox icon. By each email, it shows that they are in the Inbox folder, but when I click on the Inbox folder, those emails do not appear there. So I go back to the Unread folder and read those emails. I go back click to the Inbox, and those emails never appear there. I go back to the Unread folder, and since I read them previously, they of course do not show up there. Now they do not appear anywhere, so they are gone and I have no record of them. I thought maybe they are in the Spam or Trash folder, but they are not. Something is broken.