Yup, it looks like some problem with the combo box not recognizing that the user has made a selection. Using the dummy value worked, as did selecting the first value in the list, then selecting the selecting the second (to force the onChange event) then selecting the first (the one I wanted).

Again, this all appears to have been triggered by my editing the .form file directly to add styling.

Specific questions (if anyone is listening):
1. How to refresh the bpm file after changing the .xform? (As explained in my first post, I do a drag/drop, then delete the items created - works fine, but there must be a cleaner way)
2. Is the right way to style the .xform to edit the file directly - or was that a bad thing to do?

Thanks,
RB