If you are getting the "hardware disconnected" message in Scratch Live with your Rane hardware plugged in, you might need to reinstall your Kernel Extension file.
The Kernel Extension files (often thought of as "drivers" for mac OS) are typically used to add support for new hardware and/or filesystems.)
1. Quit all programs
2. Go to Macintosh HD > System > Library > Extensions
3. Move the 'SeratoScratchDriver.kext' to your trash.
4. Download and reinstall the latest version of Scratch Live from here.
5. Open Scratch Live with your Rane hardware connected and now check if Scratch Live detects the hardware.
If you are still having issues, please start a help request so the support team can troubleshoot with you further.