Sidebars Array not loading

Dear Support,

I have to load list (array) of all registered sidebars, if I load the following code:

print_r($GLOBALS['wp_registered_sidebars']);

in any other page for instance in header.php it shows the whole list of available, but if I use the same code in my custom fields file, it only shows 1 (the first sidebar) and the rest are not available, I have tried setting

global $wp_registered_sidebars;
print_r($wp_registered_sidebars);

but it also shows only 1 from the array... Can you please help here..

thanks