When starting mIRC just after a new version is released, the client will prompt you to download it, but beta versions of the client will direct you to https://www.mirc.com/beta.html
which then redirects you to the empty beta thread.
Similarly, when clicking Help > About and then [Check for Updates], the beta client will direct you to https://www.mirc.co.uk/beta.html
which similarly redirects to the empty beta thread.
Solution: New final releases should direct the user to https://www.mirc.com/get.html