How can I increment CPT title and slug reliably? - php

Question

I've got a custom post type called 'tasks' with an ACF front end to post each new one.
I'd like to hide the title from the end user, and have the title & slug automatically set & increment.
Task 1, Task 2, Task 3 etc.
I've tried all the code examples on here I can find & nothing seems to be reliable.
Has anyone got anything they've used in the past that works reliably?
Tried this;
add_filter('title_save_pre','auto_generate_post_title');
function auto_generate_post_title($title) {
global $post;
if (isset($post->ID)) {
if (empty($_POST['post_title']) && 'produktionsauftrag' == get_post_type($post->ID)){
// get the current post ID number
$id = get_the_ID();
// add ID number with order strong
$title = 'produktionsauftrag-'.$id;} }
return $title;
}
Just gives me a post with the title 'untitled' & the next post id as the slug
Tried this one
add_filter( 'wp_insert_post_data' , 'modify_post_title' , '99', 2 );
function modify_post_title( $data , $postarr ) {
// Check for the custom post type and it's status
// We only need to modify it when it's going to be published
$posts_status = ['publish', 'future', 'pending', 'private', 'trash'];
if( $data['post_type'] == 'task' && !in_array($data['post_status'], $posts_status)) {
// Count the number of posts to check if the current post is the first one
$count_posts = wp_count_posts('task');
$published_posts = $count_posts->publish;
// Check if it's the first one
if ($published_posts == 0) {
// Save the title and the slug
$data['post_title'] = date('Y-m') . '-1';
$data['post_name'] = sanitize_title($data['post_title']);
} else {
// Get the most recent post
$args = array(
'numberposts' => 1,
'orderby' => 'post_date',
'order' => 'DESC',
'post_type' => 'task',
'post_status' => 'publish'
);
$last_post = wp_get_recent_posts($args);
// Get the title
$last_post_title = $last_post['0']['post_title'];
// Get the title and get the number from it.
// We increment from that number
$number = explode('-', $last_post_title);
$number = intval($number[2]) + 1;
// Save the title and the slug
$data['post_title'] = date('Y-m') . '-' . $number;
$data['post_name'] = sanitize_title($data['post_title']);
}
}
return $data;
}
Does nothing, acf form page just refreshes itself