Audition output sample rate stuck at 8khz since update - Help!

As ryclark says we need to know more details of your system, particularly your audio interface, the drivers it uses, and the OS on your computer.

However, as a general comment, Audition can't always control your interface.  It depends on the type of interface and the drivers they use.  Audition communicates well with most decent interfaces with properly written drivers, but there are some that don't follow the standard.  This can be made worse if the interface is also used for general system sounds which can set the sample rate/bit depth to whatever it wants.   If this is the case, you should be able to fix this by opening the software control panel for what ever interface you have (or the generic Windows/Apple one if there isn't a specific interface) and making the change there.