I ended up ditching acf for the plugin and built everything from the ground up and used the built-in WordPress save_post hook: https://codex.wordpress.org/Plugin_API/Action_Reference/save_post
If you have a problem with actions not firing in time try adjusting the priority parameter to see if that helps, but I just made the plugin itself independent. Depending on what you are trying to achieve that might be an option for you as well @beee.
