How are you sending commands to the SPARK MAX; PWM or CAN? When in neutral, do you observe a magenta (or yellow) LED, then after it switches to brake mode do you observe a cyan (or blue) LED when in neutral? Are you mapping the joysticks/analog sticks directly to the control commands?
Please send me some video of the behavior to firstname.lastname@example.org. Please reference this CD thread.
I’m asking some the questions above to try and understand if the controller is truly switching to brake mode, or if it may be stopping due to other reasons.