If you are using KC705, then it should work.
How did you program the FPGA? There is an on-board USB-JTAG port which uses the Digilent JTAG module. This is the one that we support. If you use a Xilinx platform cable to connect to the JTAG header on the board, then it won't work.
Can you double check if the Digilent JTAG cable shows up correctly in the Vivado hardware manager?