bitrise-workflow-editor: Failed to load workflows.

I installed the latest version of bitrise cli & the workflow editor plugin. I created a folder with bitrise.yml. The workflow editor is failing to load the workflow. Am I doing something wrong?

• https://gist.github.com/bootstraponline/01c50f24ecd7f971bf6394e1699abc99

$ bitrise version
1.5.4
$ go version
go version go1.8 darwin/amd64
$ bitrise :workflow-editor version
0.9.6

$ bitrise :workflow-editor
Starting API server at http://localhost:3645
Open workflow editor in browser ...
 => GET: /api/bitrise-yml.json - 10.065492ms ()
empty output data

		}, function(error) {
			viewModel.workflows = undefined;
			console.log(error.message);
			viewModel.configureWorkflowsProgress.error(new Error("Failed to load workflows."));
		});

POST http://localhost:3645/api/spec 400 (Bad Request)
(anonymous) @ VM228:2
(anonymous) @ main.js:23338
sendReq @ main.js:23131
serverRequest @ main.js:22841
processQueue @ main.js:27448
(anonymous) @ main.js:27464
$eval @ main.js:28716
$digest @ main.js:28532
$apply @ main.js:28824
done @ main.js:23162
completeRequest @ main.js:23360
requestLoaded @ main.js:23301
main.js:57271 Error loading library