As another reply mentioned, apparently the streaming API isn't working on Model 3 (yet?).It works just fine. I wrote a couple of apps and have open source them. See Windows Tesla Auth Token Generator and My Tesla Model 3 “Keyfob”.
We recently took delivery of a Model 3 and my existing logger kept marching along, adding the 3 to the cars recognized on the account. Sure enough, the base/pull API is working on the 3 but the streaming is not.