@D. Tempest, it seems you've spent considerable time crafting your reply. Looking at your previous posts in this community, you seem from your reply to have come a long way in mastering your all-digital Model 12's operations, so congratulations!
However,
@ilstefano only made a general reference to "the latest drivers for TASCAM and Windows" associated with his analog Model 16.
The OP didn't tell us which version of the firmware is running on the Model 16, which version of Windows is on the computer, and which specific TASCAM and Windows drivers were installed.
Having that formation from the OP beforehand would be critical to solving the OP's specific issue; and for the OP to benefit from the solution that worked for you, your operating setup would need to be very similar to the OP's, yes?
It's hard to say if such detailed steps would work for the OP if the OP's firmware, OS version, and installed drivers are at this point unknown, and s/he has an analog mixer v your digital mixer.
Have you confirmed that the troubleshooting steps you've developed are generic enough to apply to all the possible Model16/Windows OS/Driver combinations? Otherwise the OP may become even more confused and waste time going down rabbit holes that don't apply to his/her operating setup.
Including references to the MAC OS when the OP is using Windows might only add to the confusion. Likewise re the section you wrote about MIDI/D.A.W. Control.
Be that as it may, what are your "steps 1 and 2" left unmentioned? Why not include your ommitted information, instead of starting with a self-numbered step "3" that might confuse some who may find this thread in the future and who may be unfamiliar with obtaining and installing the correct TASCAM and Windows drivers?
I trust you'll take these comments as a constructive critique from someone who's been providing many years of assistance to this community based on decades of real-world experience.
