The site is live, so I would rather not be changing the theme.
I'm not sure how the WP menu system could be affected by the theme
Because sometimes, for example, the theme uses what is called a custom Walker class which is a way to tap into the native wordpress nav menu output and alter it.
I do not know what you have done since posting but I do see the contact item now. The strange thing is that the Blog link is commented out. That is what lead me to think maybe a custom walker class had some effect.
<!--<li class="menu-item menu-item-type-post_type menu-item-object-page menu-item-28" id="menu-item-28"><a href="http://www.reviance.com/blog/">Blog</a></li>-->
The above is your blog link. I really don't know why that would be commented out. The blog page itself is blank so perhaps check your reading settings or some other settings in the theme that indicate which page is to list your blog archives. Maybe there is an error in that setting and the theme is denying the blog link?
You might try to get support from the theme creators.