I originally had problems running a bokeh server securely using Gunicorn+Flask and an HTTPS address. In my case, the issue came down to needing to generate a Subject Alternative Name (SAN) certificate when I made a self-signed certificate via openssl for testing.
If you’re using a self-signed certificate, that might be what you’re running into as well. See this topic on bokeh discourse towards the end of the discussion for a link to more info.
https://discourse.bokeh.org/t/help-needed-with-ssl-for-a-nginx-gunicorn-flask-bokeh-setup/6069/8