None of the MIDI tracks’ volumes can be adjusted using mixer faders. Volume can only be adjusted from the sampler plugin’s (SampleTank3) MIIDI channel output.
This is a new issue for me, the only recent change is upgraded new computer (upgraded from Win7 to Win10). I reinstalled Cubase 6 and SampleTank 3, and installed new ASIO and interface drivers successfully.
These same project files’ faders worked before the OS upgrade and fresh installs.
Everything you list “looks ok” but, let’s continue to hopefully troubleshoot this.
I don’t have a Focusrite audio interface so I am just going to be able to give you some ideas…
Many audio interfaces come with their own mixer control software (the 18i20 does). Since you freshly installed the ASIO driver onto the new computer it is possible that mixer control software was activated and now has somehow been assigned to control the volume of your midi tracks. So open that control software and take a look to see what is going on in that mixer. Hopefully you will see something there.
When I first installed the ASIO driver (which included the mixer control software) that came with my Presonus Studio 192 Mobile audio interface it did take over a lot of the volume and routing control. I was able to get past that issue as it has a “Bypass Mixer” option in that software. Maybe yours has a similar option too.