Composer Pages that are protected with a password must be served over a secure HTTPS connection. If the page is served over a non-secure HTTP connection, the password will fail without displaying an error.
To fix this, navigate to the page in Composer and click the pink "Settings" icon:
Make sure that the "Serve page over INSECURE (HTTP) connection" checkbox is not selected:
Re-save and publish the page, if necessary.
Please Sign in to leave a comment if you don't see the comment box below.