Reposting this hoping that somebody has come across it or somebody
within Adobe can put me in contact with somebody who can look into this
(customer care seems to have no idea after 3 weeks, case 140709-000247).
Here's an image of what the output looks like, what the Target offer
looks like and the DTM rule (which triggers if a data layer element is
set to a certain value, then attempts to wrap an mbox around a certain
div) if that helps.