Hi there,
The audition, play and scrub functions are not working in the sample editor. They do not produce any audio. In addition, I cannot preview processes - I can click on and apply them, but it won’t produce audio when I click ‘preview’.
All these functions used to work. Have I inadvertently disabled them? If so, how do I re-enable them?!
Are you using (or are you intending to use) the control room?
The reason I ask is that the preview channel acts differently depending on whether the control room is in use or not.
Many thanks for your response.
No, I have no use for the control room. However, I was having problems with my driver and fiddled with and activated the control room in a bid to sort out the driver issue. I am new to Cubase. Now you have risen the question, I think the control room in a likely suspect - is it now a case of simply disabling it? If so, how?
That is definitely the problem. 
Go to VST connections under the “devices” menu, then to the studio tab. There is a power button there for the control room. Turn it off. Your preview channel should work as expected then.
I could give you a big kiss right now! 
Aww! 
Awesome–glad to have helped.
After reading the Cubase directions that the scrub is routed to the control room by default, I wound up here.
However, I had to read your instruction more carefully - there is also a seemingly obvious “Control Room Mixer” at the very top of Devices. That also has a power button and it seems that’s where I should turn it off! Disabling that power button, which looks to me like I’m shutting down Control Room, does NOT fix this issue. I’m not really sure what it does.
However, as you noted - going into VST CONNECTIONS, and hitting that power button does do it.
Thanks for the help, and hope my extra point saved someone some time too.