Newbie I/O config question

I’m just starting a project to transport about 60 live concert DAT tapes into Cubase and clean them up. It’s been years since I’ve played with editing software and I’m having setup issues. I had trouble getting both recording and playback to work, but I did get one tape transferred. Then I had to pack up and move the equipment, and now I’m having trouble again. This has to be something simple that I’m missing - any advice greatly appreciated!

Setup:

Computer: Cubase LE AI Elements 9.5 running on MacBook Pro Retina, early 2015, OS Sierra
Audio interface: Scarlett 6i6
Source: Sony TCD-D8 SPDIF out

The MacBook is recognizing the 6i6. When I open the FocusRite control app, it reports that it’s connected. In MacBook Setup, the 6i6 is selected both for Sound Input and Output. If I play audio files on the MacBook (e.g. YouTube, Pandora), I can listen on the 6i6 either on headphones 1 or by feeding Monitor 1-2 to a small amp.

In Cubase I have SPDIF 1 and 2 selected for my stereo input. But I’m not getting any signal on my Cubase stereo in. Likewise, when I play a concert tape back, I can listen on the TCD-D8 but not on the 6i6 - no sound through the monitor 1-2 or the headphones.

I’d appreciate any suggestions. They may be accompanied by a good amount of josh and jive, as long as you get me running again … This has to be some very simple newbie error, but I just can’t find it.