[kamocat]

Are you sure the PWM cables aren't plugged in backwards? It's labelled on the Jaguar (barely), but not on the Digital Sidecar.
They should have the white side facing towards the sidecar.

However, if your Jaguars have a solid yellow light, then that means they are getting data from the cRIO. This means:
Your cables are plugged in correctly
AND
You have "opened" the motor controllers in your code