Uncanny Acument >> Fortitude save bug(?)

[panzhuli]

I have a cleric (class default is Trained in Fortitude) who is leveling up. I want to select the "Canny Acumen" trait in Fortitude. Here's the description of the feat:

Your avoidance or observation is beyond the ken of most in your profession. Choose Fortitude saves, Reflex saves, Will saves, or Perception. You become an expert in your choice. At 17th level, you become a master in your choice.

When I apply Fortitude, it doesn't change my Defenses stat (it is +7 before and after). Attempting to choose Reflex, however, does change the +7 to +9 (as expected). Is this a bug? Is there a workaround?

Thanks!