I actually recently received two reps from a dealer (not one from this site) that have the same issues you're describing here -where they are both chronos (one is a tag carrera and the other is a Speedmaster), but they both have non-functioning chrono dials. The top buttons have a click (sort of) which only advances one of the dials about 1/12 of a turn, while the bottom one does the same to a separate chrono dial. The primary second hand continuously runs. I'm not sure if this is how they were intended to function, however, it wasn't how they were advertised, although for the price I wasn't expecing too much. The watches look good at least and do keep time fine.
I'm hoping to find some higher quality reps that hopefully have some degree of QC applied prior to shipping through this site. We'll see how that turns out.