Hi,
If you enable the "Allow theme change in URL" which is a setting in
Site administration > Appearance > Themes > Theme settings
You will be able to see how Clean theme works in that page by adding
&theme=clean
at the end of the URL of that User Report page
You will find that the values do not flicker as you move the mouse over the page, so it is unclear why the flickering effect only happens in the Essential theme? I looked briefly at the generated CSS code for that page using FireBug, and found large sections of CSS that appears to be styling "hover" as white text on an almost grey/white background. Then in other places the text colour is set to be white and in other areas the text colour is inherited, so that could be whatever settings are in the theme, who knows. That said those may be OK in some places where it is needed, but the knock on effect that the majority of that CSS is having on other areas not investigated could be just as bad as what you and I have found in that report page.
I hope this gets resolved soon too.
Mary