Some Rich Text doesn't show up in Test Execution

I have rich text enabled in test repository. However, when in test execution some of the rich text is not displayed. For example, text that is underlined or a different color font than black does not display correctly. Some of the rich text does correctly display: bold, italics, hyperlinks, etc. 

Is there a reason that different font colors and underlining are not displayed in test execution or is this a bug?

Thank you.