It is working but I can turn on/off cards 11,12+ (only 0-9). You can change it to two digits 00-99 or 0-9, a-z. I can't see temperature and most options doesn't work (OC, Power Level etc).
BTW, MSI Afterburner also doesn't support 12+ GPU's (it can support 7 or 8 GPU's).
The latest AMD Adrenaline 17.12.2 drivers broke the Claymore temperature and fan control in compute mode. On Windows 10 v1709, you can use the Crimson Relive 17.11.4 drivers with compute mode for up to 13 AMD cards. Temperature and fan control is working and you can also set the overclock, powerlimit and voltages directly in the miner command line or config file.