Custom Image Sizes not apppearing.

Hello,

I’ve created a series of custom image sizes in my functions file however when I attempt to add a photo to let’s say a blog post the option to choose from one of the new image sizes does not appear in the Attachment Display Settings dialog box.

Here is my code:

function mysite_features () {
	add_theme_support('title-tag');
	add_theme_support('post-thumbnails');
	add_image_size('mysiteLandscape', 100, 500, true);
	add_image_size('mysitePortrait', 480, 650, true);
	add_image_size('mysiteThumbnail', 300, 200, false);
	add_image_size('mysitePost', 768, 300, true);
}
 
add_action('after_setup_theme', 'mysite_features');

I have cleared cache, regenerated thumbnails but to no avail.