This is probably simple but here goes. I loaded Halion Sonic SE 3 (ver. 220.127.116.11 Feb 2019) in the VST Instrument panel. Cubase automatically created a folder with 2 tracks and adds a mixer channel called HSSE Main. The volume control of this channel controls the overall volume of Halion and works correctly.
I then loaded a piano sound in Slot 1/CH1 and a String sound in Slot 2/CH2. I then created 2 midi tracks one for each sound/channel and assigned the proper channel to each. I then recorded some performance in each track. They both play back correctly with the correct sound. The problem is I cannot control independently the Volume or Pan of the individual sounds, Piano and Strings, using the Volume Fader of the their respective MIDI tracks.
Is this the normal behaviour of Cubase when sharing a VSTi with multiple MIDI tracks. If so, what must I do to be able to mix the project using the Cubase Mixer.