We would like to use the default featured image for our post thumbnail grid and most post pages, but use a different image on some posts.
Is it possible to check if the alternative image is present and, if it is, to load that one instead of the default featured image?
I have read through this post but it doesn’t cover what we are trying to do: https://support.advancedcustomfields.com/forums/topic/failed-to-set-featured-image-from-acf-image-block-3/
Any suggestions would be great.
You need to create a filter on the post_thumbnail_id hook. Check for the alternate image and return the ID for it if it exists.