Solved it!
The SDK update changed the assistant initiation call. You registered a device_model_id (“Raddys-magic-mirror-device-id” for example) in the original instructions, so you have to add that to the assistant.py file. (Here are instructions on manually registering a device and creating a device instance–I don’t know if an instance is required for this to work, but it’s part of what I did trying to solve this).
Open the assistant.py code and scroll down to line 124. The current call is this:
with Assistant(credentials) as assistant:
In the updated method found on Google’s dev site, it should read:
with Assistant(credentials, device_model_id) as assistant:
Where you replace device_model_id with whatever you registered before.
with Assistant(credentials, "Raddys-magic-mirror-device-id") as assistant:
Run it and it should work!