So - problem solved! The new upload (v2.1) does indeed populate to Curse Client. Here's what I've figured out, in case anyone else has this issue:
The folder name inside my package, at some point, picked up an errant space in the name. This space seems to have affected how the file gets handled on the Curse back end. Removed the space, now things seem to be fine.
Latest version now available at the link above or via Curse Client!
Cheers, and thanks!