version 16.1 gives error 500 when saving Elementor templates

I have several sites on WPEngine, and they get 500 errors when saving after editing in Elementor, deactivate Yoast, then it works.

Error logs for PHP show:

[Tue Apr 06 10:10:10.473223 2021] [php7:error] [pid 18029] [client XX] PHP Fatal error: Uncaught TypeError: Argument 1 passed to Yoast\\WP\\SEO\\Builders\\Indexable_Hierarchy_Builder::build() must be an instance of Yoast\\WP\\SEO\\Models\\Indexable, bool given, called in /nas/content/live/XX/wp-content/plugins/wordpress-seo/src/integrations/watchers/indexable-ancestor-watcher.php on line 175 and defined in /nas/content/live/XX/wp-content/plugins/wordpress-seo/src/builders/indexable-hierarchy-builder.php:102\nStack trace:\n#0 /nas/content/live/XX/wp-content/plugins/wordpress-seo/src/integrations/watchers/indexable-ancestor-watcher.php(175): Yoast\\WP\\SEO\\Builders\\Indexable_Hierarchy_Builder->build(false)\n#1 /nas/content/live/XX/wp-includes/class-wp-hook.php(294): Yoast\\WP\\SEO\\Integrations\\Watchers\\Indexable_Ancestor_Watcher->build_post_hierarchy(204)\n#2 /nas/content/live/XX/wp-includes/class-wp-hook.php(316): WP_Hook->apply_filters(”, Array)\n#3 /nas/content/live/XX/wp-includes/plugin.php(484): WP_Hook->do_action(Array)\n#4 /nas/content/live/XX/wp-inclu in /nas/content/live/XX/wp-content/plugins/wordpress-seo/src/builders/indexable-hierarchy-builder.php on line 102, referer: /wp-admin/post.php?post=204&action=elementor

Yoast 16.1, Elementor 3.1.4 , Elementor Pro 3.2.1, WordPress 5.7, PHP 7.4