AFAIK, railways didnt issue any circular about refund of CK. But the circular for 50% refund on cancellation for Suvidha (for which the charges are CK fare) was misinterpreted by medias.
If i am wrong, pls correct me
IR said that "The Railways is also toying with the idea of giving refund
on cancellation of confirmed tatkal tickets, the percentage
of...
more... which would be calculated based on a time frame."
But the media made it as 50 %