Apparently I was missing a theme update that hadn’t shown up before. Updating to Version: 1.6.134 appears to have fixed the problem.
@hm11 If you are having the same issue that I was then you may want to check for updates for the theme (not just the Companion Plugin) and see if there is a new version to install. As for the rollback, I had simply downloaded a backup of the entire website before upgrading to WordPress 5.5 in case things would break.
@cristianbarbu Thank you for your assistance as I had no idea that there was a theme update in addition to the plugin update. As far as I can tell everything is working as expected now.
