How can I track progressive profiling form submits in Bizible?

I've discovered that Bizible doesn't like progressive profiling. Bizible will track submits on the form when the first set of fields are presented (first name, last name, email, company, title). But subsequent form submits, where we present only 2 custom questions, are not captured in Bizible.

I've discovered a Bizible support article that deals with this issue ("Ghost" or "Progressive Profiling" Forms Setup). But by web dev says that while he could implement this fix on our CMS, the Marketo form and landing page editors do not offer the necessary access to implement the required code.

Has anyone else come across this problem and been able to fix it? One solution is to stop using progressive profiling forms but I'd prefer not to.