Looks like a lot of other people have had this issue.
I'm able to generate a token, but attempting to use it when hitting the Device API results in a 403 Forbidden.
(https://api.ciscospark.com/v1/devices)
I also specified the scope to use the api (spark:devices_read scope / spark:devices_write / spark-admin:devices_read / spark-admin:devices_write)
What is the solution?