I installed the IoT XDK and loaded the blink example. The LED on pin 13 blinks! Great! I changed the interval from 1000ms to 100ms and to 3000ms and reuploaded to the Edison. No change. Light still blinks every second same as before. I even changed the app version info to try to force it to see the update.
I must be missing something obvious.
The latest software update appears to have solved my issue. I can now vary the duration of the LED pause in the sample code and successfully update my app on the Edison.