Track and Set Regarding options are missing in Dynamics 365 App for Outlook

When you are viewing an email and open Dynamics 365 App for Outlook, the Track and Set Regarding options are missing. 

NOTE: If the Track and Set Regarding options appear but only the button icons are missing, see the following article:

Buttons such as Track and Set Regarding are missing in Dynamics 365 App for Outlook

https://support.microsoft.com/help/4464349

Cause 1: Your Dynamics 365 security role does not have access to the App for Outlook Dashboard

Cause 2: The sitemap of the App for Outlook app module was customized and the dashboards area is no longer configured to use the App for Outlook Dashboard.

Resolution 1: 

1. Access the Dynamics 365 web application as a user with the System Administrator security role.
2. Navigate to Settings, click Customizations, and then click Customize the System.
3. Click Dashboard and then select the App for Outlook Dashboard.
4. Click Enable Security Roles.
5. Verify the option is set to "Display to everyone" and click OK.
6. If the option "Display to everyone" was not selected previously and you have now corrected it, click Publish All Customizations. Clear your browser cache and then close and reopen Outlook.

Resolution 2:

Verify the default dashboard of the App for Outlook app module is configured to use the App for Outlook Dashboard. Refer to the Limitations when customizing Dynamics 365 App for Outlook section of the Deploy Dynamics 365 App for Outlook article.