If I had to guess, I would say that you are probably running into a security restriction implemented by IE.
You might take a look at the following page:
In particular, the statement on that page that seems most relevant is:
"For security reasons, data URIs are restricted to downloaded resources. Data URIs cannot be used for navigation, for scripting, or to populate frame or iframe elements."
My assumption here is that WebViewers in WebDirect are implemented using an iframe element. I do not know this as a fact, but it should be easy enough to confirm/refute this by examining the DOM or page source of your WebDirect page.
Very best regards,