The SSH connection between an SSH proxy and an SSH client can be blocked in the browser by clicking the red arrow on the right side of the screen.
This is called a proxy redirect and can cause the connection to break in the middle.
When an SSH connection is broken, it is blocked by default.
The workaround is to disable the proxy redirect by changing the value of the proxy_server_ip attribute of the user agent in your browser, e.g. by typing about:config in your web browser.
The default value for proxy_user_agent is https.
To set the value back to https, set the proxy type to ssh in the About section of the About dialog.
To disable proxy redirect, change the proxy directive of your user agent again, e and go back to the About page.