CC121 and Cubase Update 10.0.40 not working 
I have had after the C10 update that the CC121 USB Driver was not working anymore.
Think also a Windows 10 Update came alongside.
I just reinstalled the CC121 Driver, and everything worked OK again.
Works fine here, had no problem with CC121 after upgrading to C10.0.40
Just purchased the CC121 today. Everything works fine except the motorized fader cannot control Cubase 10.0.40.
The opposite works - track fader with mouse triggers successfully the motorized fader.
Sorry to hear that. Didn’t experience any problem with CC121 and C10.0.40 update here, but I’m still on Win 7.
Reinstall the Yamaha Driver (separate dir)…
Maybe it could be related also with usb port which You use. In manual they said that port used during initial connection has to be used as only one for future use with CC121. I didnt noticed any difference when different port used, but who knows.
For chaning the USB port, uninstall the Yamaha Universal Midi Driver.
Take out the CC121 from USB port and put it in the USB port you want.
Reinstall the Driver.
I had this same problem and found a way to fix it from another thread.
Go to page 23 of the CC121 manual…
The touch sensitivity of my fader was set to 2. I turned it up to 8 and suddenly it works again. The “record LED” touch test showed me that it didn’t even detect touch when set to 2. Settings 3 and above seemed to detect touch.
Thank you very much. Finally it was a hardware issue. The usb port on the cc121 had not a correct touch stability with the usb cable. I went to the Yamaha service near here, they confirmed the issue and they changed the unit.