What could cause a theme to ignore html markup?

Hi guys,

Kind of a general question here–I can’t provide a URL because I’m developing a redesign on the back end.

What could cause a theme to call the_content but display that content without any embedded markup? Simply: html like does not render italics. In-line style does. The same is true for image size–a width specification doesn’t resize the image, but styling the width via style=”width:x;” does.

However, when viewing the page source, the markup is still there. still wraps the text–the text just displays as plain.

What could cause this? What should I look for? I’m working with a theme I didn’t design, and I’m not sure what to try and correct.