Error when saving post

I am getting the following error when saving a post that has a relationship attached to it… The error only happens once, then after I click update on the post, it seems to be fine the second time.

Any help or ideas on this?

Notice: Trying to access array offset on value of type bool in /home/…/wp-content/plugins/post-2-post-for-acf/acf-post2post.php on line 99

Notice: Trying to access array offset on value of type bool in /home/…/wp-content/plugins/post-2-post-for-acf/acf-post2post.php on line 130

Warning: Cannot modify header information – headers already sent by (output started at /home/…/wp-content/plugins/post-2-post-for-acf/acf-post2post.php:99) in /home/…/wp-admin/post.php on line 231

Warning: Cannot modify header information – headers already sent by (output started at /home/…/wp-content/plugins/post-2-post-for-acf/acf-post2post.php:99) in /home/…/wp-includes/pluggable.php on line 1296

Warning: Cannot modify header information – headers already sent by (output started at /home/…/wp-content/plugins/post-2-post-for-acf/acf-post2post.php:99) in /home/…/wp-includes/pluggable.php on line 1299