How can I send images as an album in WhatsApp Business API?
When sending an image as an album from the WhatsApp Business API, you will need to send at least 4 images in succession. If the user's conversation view is currently active when the images are received, then the album view is unavailable until the next visit.
An album will not be created if any of the following criteria are met:
Images with captions
Unread divider - user sees some images, but not the rest