Missing Matrix Modulator on certain instruments

Total loss here… I’ve been through the manual and spent hours online searching for the answer to this. All I want to do is to assign aftertouch. My keyboard transmits aftertouch, and I’ve managed to set this up and it works with some patches in Halion Sonic 3. After reading the manual I understand now that I can assign what aftertouch does within the Modulation Matrix. However, on some sounds, like for example ‘Latin Rock’ (Electric Guitar in factory content) there is no option to edit the Modulation Matrix. I’ve attached screen shots, and as you can see the patch ‘New Age Argh Choir’ has the option to view the Matrix. So just to be clear, I mainly want to use my controller keyboard’s aftertouch rather than the modulation wheel for things like vibrato etc. Anyone have any ideas? Thanks.