Compatibility with WordPress 5.5?

Just updated to WordPress 5.5, and it looks like this plugin no longer works. Clicking on the Link Pages button on the left-hand side of my WordPress dashboard takes me to a blank white page. (I tried both Firefox and Chrome; same deal. Logging out and back in makes no difference.)

Weirdly, the page itself (https://www.bardicfool.com/411) still exists; I just can’t edit it.

Am I missing a troubleshooting step here, or does the plugin actually not work with the new version of WordPress? Everything was fine before I updated.

Thanks for your help!