Headlines not rendering correctly in visual editor

Hello All,
This is a new install of WordPress 3.1.2 using the Weaver theme.

In the visual editor, headlines (h1, h2, h3, etc.) appear correct at first, but when any other element is added inside the headline, the color/size/weight styles are replaced by the ‘paragraph’ style in editor.

The HTML is fine and shows the correct structure, example: <H1><span>Text</span></H1>
Posts preview fine, but the WYSIWYG displays it incorrectly.

I’ve tried it using PCs/Macs, Chrome, IE, and Firefox. The WYSIWYG consistently shows headlines in paragraph style when any tag is placed inside the headline. In other words, placing <strong>, <em>, or <a> inside an <h2> or <h3> tag has the same behavior.

I’m not sure if this is a theme CSS issue or an issue with TinyMCE.

Has anyone encountered this before? I’d like to fix this for the end users if possible.

Thanks!