Fixes needed in plugin

Using 4.9.4 I had to make the following modifications to get this working properly:

Issue: https://drive.google.com/file/d/1YAeSuG7ppHIp5DXr6Vyy1jfTZEgf0ZPh/view?usp=drivesdk

Quick fix:
/wp-content/plugins/simple-post-type-permalinks/includes/Module/Admin.php:186

			//$front = '<span class="front">' . esc_html( substr( $wp_rewrite->front, 0, - 1 ) ) . '</span>';
			$front = esc_html( substr( $wp_rewrite->front, 0, - 1 ) );

Issue: Passing "sptp_permalink_structure" => "foo/%post_id%" was leaving the permalink field disabled. Checked the code and it appears to be setup to work like this instead:

If you register post type register_post_type( 'foo' the plugin expects post type to be passed in like this: "sptp_foo_structure" => "foo/%post_id%" (note the “foo” being used in the variable name).