Thanks for your suggestions ptrblck!
Actually, I do just want to unsqueeze the tensor, thanks for pointing that out.
The suggestion to overfit a small dataset is very helpful. Doing that, I’ve made a much quicker loop of experimentation and evaluation. I haven’t solved the problem yet, but I feel I’m working toward it in a much more purposeful way.
I’ll check back in when I have a firmer handle on what’s happening.