UPDATE: I got my 16.0.2 (should also work for 16.4.2) working as a 16in/16out audio interface over firewire on Catalina. Turns out, during the installation of the firewire drivers, apple's new security features disable the drivers on installation, with no warning!?
You'll know if this is the case if you follow these instructions:
Also, if you check on your StudioLive 16.0.2 firewire mixer System Menu >> "Page 3: Digital" the status will say "no driver" if the driver has been disabled.
To check for disabled software, follow this answer (it says OS X 10.13, but works for 10.15):
To rectify, follow these instructions (again, it says OS X 10.13, but works for 10.15):
Won't get UC working, but will get your mixer taking to your computer. Hope this helps!