I went for the same 2 days ago. Reservation clerk said that blank paper ticket are not being issued for any class. I asked that GST is not applicable to SL class than why blank paper tickets are not being given in SL. Clerk said that they are ordered by higher officials to not issue in any class. :(
Though he said that these tickets will be resumed after sometime once GST calculation is fixed in systems. Not sure how much of this information is true.