I have just bought the Logitech MX Master as well and was very surprised that horizontal scrolling didn’t work in Cubase. It’s basically what I bought it for.
Steinberg can’t sell to me that it’s too hard to implement in Windows. I am a Software Architect, I know what i’m talking about. Reaper can do it, Excel can do it, Chrome can do it; shall I continue? (the list probably continues with ProTools, FL Studio, Ableton Live, PreSonus Studio One, Bitwig and all of the DAWs I didn’t mention).
This should be native to Cubase. Using external tools to simulate this behavior is just nonsense.
Please Steinberg, just buy the Logitech MX Master mouse for 65 euros and fix this in Cubase 9 so we can improve our workflow. It’s not rocket science.