Since updating to Mac OS X El Capitain, my Fast Track C400 interface as stopped working. I believe it is to do new driver signing system. (i.e. kext extensions management) However, I have disabled driver authentication (SIP) and uninstalled and reinstalled the the C400 drivers several times. The device is not recognized in the C400 control panel, or in the Mac System Preferences sound settings. The device lights up when connected, but will no longer see the device in any software. This is a major disruption to my work as my main interface is out of action. Has anyone any ideas or had similar trouble?