Hi, Roberto.
I’ve not had any luck resolving this issue through any route. I can only assume Apple changed something somewhere along the line with how playback and recording is handled. I found an old DVD I made of Mountain Lion years ago. I’m going to attempt taking a Carbon Copy Clone of my hard drive, wiping it, and trying to install an old OS just to use Cubase 6. It’s very frustrating. I have a layout that I’m very used to and am not ready to upgrade. I’ll report back with any findings I have.