Why doesn’t my insert query work?

You have the following for the table name: $wpdb->prefix . "wp_list_press"

Check your actual prefix and table name. In a WP installation using “wp_” as the prefix, the above would result in “wp_wp_list_press”. Is that the table name in the db or is it just “wp_list_press”?

If the table in the db is “wp_list_press” then the above should be $wpdb->prefix . "list_press";

Not sure if this is contributing to the issue or not, but your data array has fewer elements than your format array.