The codec still functions after losing MCLK during central microcontroller programming. The audio will initiate again after MCLK is returned, however, this is not the recommended procedure. You will experience a disconnect/reconnect "popping" sound. The codec has a SHDN control bit in register 0x45 that places the codec in standby. As long as power supplies remain constant, the codec will not need to be reprogrammed. The codec should be placed in standby prior to programming of the microcontroller to ensure proper functionality after coming back online.