Let's Encrypt: invalid response from /.well-known/acme-challenge/ when running certbot --apache (Apache, Ubuntu 20.04)

I have a number of sites on a new Ubuntu 20.04 server, using the WP image, using Apache virtual hosts.

When setting up this particular website, by running certbot --apache and selecting the domain and www version, I get this error:

Domain: website.com Type: unauthorized Detail: Invalid response from https://website.com/.well-known/acme-challenge/KfHqC9jlLM4kDrCkXEVCbWptpRw5sM8IEW1KrkHHdec [2606:4700:3031::ac43:9a53]: “<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">\n<html><head>\n<title>404 Not Found</title>\n</head><body>\n<h1>Not Found</h1>\n<p”

Domain: www.website.com Type: unauthorized Detail: Invalid response from https://www.website.com/.well-known/acme-challenge/Tu_rA1qZqphdzQ46_Jb6UTHERvuUsme4-G-WQmdVP4c [2606:4700:3035::6815:309f]: “<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">\n<html><head>\n<title>404 Not Found</title>\n</head><body>\n<h1>Not Found</h1>\n<p”

My website.com.conf in sites-available looks like:

<VirtualHost *:80> ServerAdmin admin@website.com DocumentRoot /var/www/website.com/public_html ServerName website.com ServerAlias www.website.com

    <Directory /var/www/website.com/public_html>
        Options Indexes FollowSymLinks
        AllowOverride All
        Require all granted
    </Directory>

    ErrorLog ${APACHE_LOG_DIR}/error.log
    CustomLog ${APACHE_LOG_DIR}/access.log combined

    <IfModule mod_dir.c>
        DirectoryIndex index.php index.pl index.cgi index.html index.xhtml index.htm
    </IfModule>

</VirtualHost>

I have recently installed SSL certificates on all of my other sites on this server without an issue. What might be the problem here?