Brian,
I had the same issue and now it looks solved (tested on IE and FF).
Originally my URL followed http://s[siteID].t.eloqua.com/e/f2.aspx?elqFormName=[FormName]&elqSiteID=[SiteID]&=<span class="eloquaemail">EmailAddress</span> I got this from the URL builder on Blind Form Submit Links: Complete and Submit Forms with a Single Click. If you did not use this skip to Part 2:
Part 1.
It seems the URL builder is missing a =emailaddress before the <span class="eloquaemail">EmailAddress</span> . It is also missing the &TrackedField=StaticValue at the end of the URL. So the URL should look like http://s[siteID].t.eloqua.com/e/f2.aspx?elqFormName=[FormName]&elqSiteID=[SiteID]&=emailaddress=<span class="eloquaemail">EmailAddress</span>&TrackedField=StaticValue.
Part 2.
I also followed http://topliners.eloqua.com/community/do_it/blog/2014/05/15/how-to-adjust-blind-form-submits-to-track-clicks to enable clicks so ultimately the UR looks like http://now.eloqua.com/e/er?s=[SiteID]&lid=[RedirectURL#]&emailAddress=<span class="eloquaemail">EmailAddress</span>&TrackedField=StaticValue
I am not sure if adding the missing text fixed it or having it as a Redirect link, but in any case it looks solved on my end.
Thanks,
Eric