Some Internet Explorer users can not see some button icons due to the security policy on their system. The buttons are still there and functional (as are the tool tips if you hover over); you can click on them and the system will work properly, however they just look like blank space. This is not an issue with Firefox or Chrome.
Buttons Displayed Properly
Correcting the Problem
To correct this issue, contact your local administrator to adjust the Internet Explorer Security Settings for Font Download to Enable or Prompt for this site. As a .mil site, this site should be in a “protected” zone. Alternately, use Firefox or Chrome.