HTTPS error on custom domain

I am trying to set up a custom domain for my Glitch project but HTTPS requests are failing with ERR_SSL_PROTOCOL_ERROR (Chrome) or (35) error:14077419:SSL routines:SSL23_GET_SERVER_HELLO:tlsv1 alert access denied (curl). Turning proxying on and using flexible SSL in my Cloudflare settings won’t fix anything as the connection to Glitch will still be over HTTP. How can I fix this?

I don’t think there is too much you can do about this, contact support@glitch.com for assistance.

You could use cloudflare for ssl. simple, easy.

True, but you won’t get encryption from cloudflare to the host if the ssl on the host is broken.

I tried, it just gives a Cloudflare host SSL error page. If I put it on flexible mode then it will still be HTTP between Cloudflare and Glitch.