I have a facet that just won't display on the search page. Is there some weird order that things have to be done for it to work? The customer has 2 sites with identical facet configuration. Site 1 returns array range values in the /api query, and site two returns empty arrays for the range. This is so strange.

The API doesn't return it? Have you rebuilt the search index recently? And are you sure that the WSR configurations are identical?

I'm going to verify everything on Monday and report back.