movabletype migration problem with monthly archive links

I thought I was going to make it through a MT to WP migration without needing any help, but not quite. Everything is fine save for my monthly archive links. They still resolve to old MT templated pages. The misbehaving site is here: https://www.lisamulvey.com

I was following the instructions laid out by Kevin Donahue at: https://blog.kevindonahue.com/archives/2006/11/18/how_to_switch_from_movabletype_to_wordpress/

But I was unable to get the last point he made, to use the MT-Redirect function to get MT to export a proper .htaccess file, to work. When I tried to create the redirect.php file, it just threw errors over and over. Frustrated with that, I went with Alex King’s individual entry archives rewrite solution, which seems to have made all the categories and the individual entries properly redirect to the WP entries, but the monthly archives are still not right.

I suspect I made need to do something with the .htaccess file, but I’ve read so many ways to do things that I’ve become quite confused, especially since the redirects are in place for individual and category links. How to I fix just the monthly archives?