Meantime, enable wp_debug and wp_debug_log and after an error, look at wp-content/debug.log to see if anything gets logged there.
I can’t see a a debug log in wp-content, but when I enabled wp_debug and went to the website, I saw this at the top of the site:
`Deprecated: Non-static method PNE_Settings::inject_meta() should not be called statically in /var/www/wordpress/wp-content/plugins/press-news-events/custom-post-type.php on line 26
Deprecated: Non-static method PNE_Settings::auto_archive() should not be called statically in /var/www/wordpress/wp-content/plugins/press-news-events/custom-post-types/event.php on line 11
Deprecated: Non-static method PNE_Settings::inject_meta() should not be called statically in /var/www/wordpress/wp-content/plugins/press-news-events/custom-post-type.php on line 26
Deprecated: Non-static method PNE_Settings::inject_meta() should not be called statically in /var/www/wordpress/wp-content/plugins/press-news-events/custom-post-type.php on line 26
Deprecated: Non-static method PNE_Settings::auto_archive() should not be called statically in /var/www/wordpress/wp-content/plugins/press-news-events/custom-post-type.php on line 39
Deprecated: Non-static method PNE_Settings::auto_archive() should not be called statically in /var/www/wordpress/wp-content/plugins/press-news-events/custom-post-type.php on line 39
Deprecated: Non-static method PNE_Settings::auto_archive() should not be called statically in /var/www/wordpress/wp-content/plugins/press-news-events/custom-post-type.php on line 39
Deprecated: Function Elementor\DB::is_built_with_elementor is deprecated since version 3.2.0! Use Plugin::$instance->documents->get( $post_id )->is_built_with_elementor() instead. in /var/www/wordpress/wp-includes/functions.php on line 5383`
Thanks again for all your help so far.