Alter Featured Image on Blog Does not work

Hey condonpb,
Thanks for the FTP access, but I couldn’t login to WP with the admin login, nonetheless I tested your function on my demo site and regenerated my thumbnails and it worked correctly

add_filter( 'avf_modify_thumb_size', 'enfold_customization_modify_thumb_size', 10, 1 );
function enfold_customization_modify_thumb_size( $size ) {
$size['entry_with_sidebar'] = array('width'=>845, 'height'=>580);
$size['portfolio'] = array('width'=>845, 'height'=>580);
return $size;
}

Perhaps this code near the top of your child theme functions.php is causing a conflict:
$avia_config[ 'imgSize' ][ 'featured' ] = array( 'width' => 1500, 'height' => 555 ); // images for fullsize pages and fullsize slider
try removing this and adding it to your enfold_customization_modify_thumb_size function like this:

add_filter( 'avf_modify_thumb_size', 'enfold_customization_modify_thumb_size', 10, 1 );
function enfold_customization_modify_thumb_size( $size ) {
$size['entry_with_sidebar'] = array('width'=>845, 'height'=>580);
$size['portfolio'] = array('width'=>845, 'height'=>580);
$size['featured'] = array( 'width' => 1500, 'height' => 555 );
return $size;
}

and regenerated your thumbnails again, and check.

Best regards,
Mike