I have a rails app that hooks into dropbox. I'm currently attempting to make a delta call, but I continuously have a Access token not found.: {"error": "Access token not found."} which is an OAuth2::Error from the oauth2 gem.
The image below shows my request and response:

a) is the request formatted correctly? The app was working before, but I hadn't touched it in 3 months, and then it stopped. Things like the urls for the api endpoints changed, so I've been bringing it up to speed. It seems as if the authorize callback and /oauth/token calls go through smoothly. It just stops here.
b) if it is correct, any thoughts? I've revoked user access to the app many times, and I don't have an old access_token stored anywhere and I do get a new one when i re-register the app. I haven't tried the disable access token endpoint yet, but I will after letting this post linger