Attachment Display Settings – SIze Drop Down Box stopped working

hi,
I’m having issues with the Image size drop-down box in the Attachment Display Settings. My only option is full size. (before I could choose medium, small, thumbnail, etc)
I’ve tried following the advice of the other threads open with the same issue, however, their solutions are not working for me.
I’ve already downloaded the simple image sizes plugin and added the following code:

/ New thumbnail size
$avia_config[‘imgSize’][‘newthumbnail’] = array(‘width’=>200, ‘height’=>200);

function avia_change_image_size_array($sizes) {
global $avia_config;

$avia_config[‘selectableImgSize’] = array(
‘square’ => __(‘Square’,’avia_framework’),
‘featured’ => __(‘Featured Thin’,’avia_framework’),
‘featured_large’ => __(‘Featured Large’,’avia_framework’),
‘portfolio’ => __(‘Portfolio’,’avia_framework’),
‘gallery’ => __(‘Gallery’,’avia_framework’),
‘entry_with_sidebar’ => __(‘Entry with Sidebar’,’avia_framework’),
‘entry_without_sidebar’ => __(‘Entry without Sidebar’,’avia_framework’),
‘extra_large’ => __(‘Fullscreen Sections/Sliders’,’avia_framework’),
// New thumbnail size selection
‘new_thumbnail’ => __(‘New Thumbnail’,’avia_framework’),
);

$sizes = array_merge($sizes, $avia_config[‘selectableImgSize’]);

return $sizes;
}
add_filter( ‘image_size_names_choose’, ‘avia_change_image_size_array’, 10, 1);

Thanks so much for your help,