BuddyPress.org

You aren’t passing the arguments correctly, they need to be an array. Try this:

$args = array(
	'type'    => 'full',
	'html'    => false
	);

$mg_avatar = bp_loggedin_user_avatar( $args );

Exactly what are you looking to do?

I always use bp_core_fetch_avatar, it’s better documented and avoids the filter, which could be the issue.

$args = array(
        'item_id' => bp_loggedin_user_id()'
	'type'    => 'full',
	'html'    => false
    );

$mg_avatar = bp_core_fetch_avatar( $args );

Try that