I have a wordpress site that has thousands of images in the uploads folder that are connected to posts in a custom post type. What would be a good way to regenerate these images to create new thumbnails?
wp-content/uploads images wont regenerate if they are not shown in the Media Library because those media ID's needs to be there in the database.You need to first add your images on the media libray with the help of add-from-server plugin.
Then with regenerate-thumbnails plugin you can then regenerate all of you images.
Hope that helps!!