Custom class no matches found

Permalink
so i try to learn about block function.
i try to apply following code
public function getThemeBlockClasses()
    {
        return array(
            'image' => array(
                'image-circle'
            )
        );
    }


when i try to the design & custom edit
on the custom css field the 'image-circle' not displayed instead 'no matches found'

 
rge replied on at Permalink Reply
Check the following:
The code you provided should be in page_theme.php.
The class "image-circle" will only be available on the block "image".

It possible that you need to clear the site cache. This can been done via settings => clear cache.
KevinKP17 replied on at Permalink Reply
yes i already select the image block. still no matches
clear cache, turn off all setting
still the same

is this a bug? or just me?