Yes, I have an open support ticket for this. I'm trying to get resolution as fast as possible. Thought I'd give the Community another try while support looks into it. Thanks.
Ah, I found your ticket. I took a look at the HTML of the email in my inbox and I can see the open pixel is being commented out down at the bottom.
<!-- Email Body : END --
<img src="http://mkto-sj220037.com/trk?t=1&mid=MDM3LU9RSy0yNjA6Mjc0OjA6MDowOjE0MjA6MDowOnN2YW5kZXJiZXJnQG1hcmtldG8uY29t" width="1" height="1" style="display:none !important;" alt="" />
<p><font face="Verdana" size="1">This email was sent to svanderberg@marketo.com. If you no longer wish to receive these emails you may <a href=
"http://mkto-sj220037.com/u/lFQ0Y000Y0000K0900G080O"
>unsubscribe</a> at any time. </font> </p>
</body>
</html>-->
</body>
So the open pixel can't ever load when someone opens the email. I'll confer with the engineer that has your ticket as well.