Lars,
Thanks for the quick reply.
I checked versions. I have 1.48.xx which comes with HANA One on AWS. While that didn't match 1.50.xx as you said to look for, it did get me to think about connections rather than the model. I turns out that when I upgraded and re-implemented my model in SPS5/Rev48, I named the package "Sales" rather than "Demo". The data connection (.odc) file embedded references to Demo and thus couldn't fine tables within that package. Rather than Excel complaining that it couldn't find the Demo catalog, which would have been easy to figure out, its' message was more generic and thus more difficult to figure out.
So, while the version wasn't the issue you did get me thinking in the right direction. Thanks for your help.