BourbonySage isn't building dist/styles directory

Trying to use BourbonySage, v.8.5 and keep getting a 404 for main.css. Looks like the dist/styles directory isn’t getting built, but scripts is getting built.

There’s little difference here from Sage v.8.5.1 except that I need Bourbon, not Bootstrap. Yet, swapping info between bower.json files doesn’t solve the problem. Something is awry in BourbonySage build that I’m unable to fix.