Can’t Update ACF Checkbox & Select Fields via Make – 500 Error or Blank Output

[Rlor]

Hi all — I’m trying to use Make.com to update a WordPress custom post type (student-resources) that uses ACF fields, including:

• title, description, link (text)
• helpwith (checkbox)
• resourcetype (checkbox)

The data comes from a Google Sheet, and I’m sending it via either the HTTP module or the WordPress > Make an API Call module to: wp-json/acf/v3/student-resources/{{post_id}}

What’s going wrong:

• Sometimes I get a 500 Internal Server Error, especially when helpwith or resourcetype are included.
• When the request does succeed (200 OK), the ACF fields are empty. The post is created/updated, but the ACF fields don’t save.

What I’ve confirmed:

• JSON output is valid
• Field names match ACF field keys (e.g. "helpwith": ["adhd", "anxiety"])
• ACF to REST API plugin is installed and active
• User has permissions
• Post ID and post type are correct

Example Payload:

{
  "acf": {
    "title": "test",
    "description": "test",
    "link": "www.test.com",
    "helpwith": ["adhd", "anxiety", "body_image"],
    "resourcetype": ["Articles"]
  }
}

Any idea what might be breaking this inside Make? Is there a known quirk when sending array fields to ACF via the API?

Thanks so much — happy to share more screenshots or exports if helpful.

blueprint.json (43.4 KB)