Ok, updating this thread also.
This is a picture of the cutting up there on the left with a node way low on the cutting and no node on top, taken about 10 days after realizing that there was actually only one shoot-capable node, and it was buried under 4" of mix. I repotted it in a different mix right away, with just that tiny little 1/2" cutting end under the soil. I wanted to plant sideways, but roots were all over the lower portion of the cutting, so I went upright (carefully).
No root activity seen on sides of cup after transplant (yet) but the shoot has doubled in length in 10 days, and leaves are forming where none were before. Hoping this one makes it! I think I'll probably lose my recent emergency transplant, but still have a couple more behind this, so ...