Are you sure the post you are updating has an ID of 13? What type of field are you attempting to update? Is the field a sub field of a repeater or flexible content field? Where are you trying to see if it’s been updated?
Welcome to the Advanced Custom Fields community forum.
Browse through ideas, snippets of code, questions and answers between fellow ACF users
The most recent ACF Chat Friday featured a live demo of how to register CPTs directly in the plugin, one of our most requested features. Check out the summary below for a replay of the demo, and don’t forget to register for the next session! https://t.co/k2KQ3WWBAz