It appears that new structural changes brought by Bluemix's shift to Diego has created a few problems for reference design AV04. Whenever a command is issued from the Alexa, such as 'go', a stream of unrelated MQTT messages is sent to the board, rather than a simple go command. Because the firmware is unable to recognize these messages, it crashes.
If you experience this issue please attempt the following steps:
1) Go to your node RED flow (see step 5 of AV04)
2) Scroll down and delete the lines or wires that connect the 'Device Payload' and 'Retain Light Value' nodes to 'Output to dashboard' by selecting them and pressing the delete key.