No longer able to override "Oops" message

I use the [rtmedia_gallery] shortcode on various pages of my website to allow users to upload images. Over a year ago I created the below function in my functions.php file to override the default “Oops…” message that appears when no photos have been uploaded. The function worked up until recently, but now the default message appears. Any idea what the problem is?

function custom_no_media_found_message_function( $message ) {
$message = "Custom Message Comes Here ... !";
return $message;
add_filter( 'rtmedia_no_media_found_message_filter', 'custom_no_media_found_message_function' ,10, 1 );