If you have 'X items to review' in the account register or account list, and, even after changing the view of the account (such as to view reconciled transactions) you can't find the missing item, then it is possible you've got some corruption in the file.
Once you have removed the corruption or deleted the statement, you may need to download the transactions from your bank again, remembering to specify a date range (should your bank only give you transactions since the last download).
Keywords: account list, statement, register