Clicking on email notification pop-up won't open the email message

When I receive pop-up email notifications through Outlook, I used to be able to just click on the pop-up and it would open the email message. When I click on the notification now, nothing happens except that the notification goes away. In addition, subsequent emails that come in populate a notification but the notification is the same one that I previously received (for example, if the first email I received upon opening Outlook was from Sender A, I will get a notification from Sender A and clicking on that does not open the email. When I get an email from Sender B, I get another notification but it is the same notification as I received from Sender A; again, clicking on it does nothing except to dismiss the notification). If I instead click "dismiss" on the notification, then the new sender's information on the subsequent notification will be accurate. 

Can this be fixed? How can I again get the email message to appear when I click on the email notification?