ROM-Reader for Super Nintendo / Super Famicom Game Cartridges

Connect the missing D8-D15 lines and the byte pin and use 16bit mode if you followed the "8bit Flash" pinout from pinout.xls .

Or if you really connected the flashrom following the "16bit Flash in 8bit Mode" pinout from pinout.xls try the V1.3 I just uploaded and see if it fixed flashing in 8bit mode.