Nothing surprising. The certificates clearly note that the tickets will be issued in C for business, not J, and therefore only get basic mileage on non-NAmerican routes. In fact, C is discounted business, so when you use these certificates, AC is selling Amex or CIBC [or Diners in the past] two discounted tickets for the price of the full fare one. And of course, the "free" ticket earns no mileage. As noted, this has been discussed at length on several previous threads about these sorts of tickets.