Page title says 'Updating. . .' but plot is not generated

[rraadd88]

I took demo code from dash's tutorial (Multiple inputs) and built a webapp using this template i.e. dash-heroku-template. In that, I simply incorporated the dash code in app.py as suggested ( below # Put your Dash code here). Here's my code: github repo Offline tests with gunicorn do work (test command: gunicorn --log-level=debug --bind 0.0.0.0 app:server) but at heroku there is a problem.

At Heroku, The build was successful. But the plot seems to have rendering problem.
Page title says 'Updating. . .' but the plot is not generated. Link: webapp.

Any suggestions?