Hi Johan,
What version are you upgrading from?
Since the 2.3 release (as
discussed in this comment during our redesign of the search/browse pages in 2015), the individual facet headers in AtoM's search and browse pages are only displayed if there is more than 1 result to show. If there are 0 or 1 results for a particular facet (meaning that there is either nothing to facet, or only 1 facet meaning that applying it will not change the result set at all), then that facet will not display, to simplify the available options for the user.
In the documentation, this is mentioned in the Note admonition in the Facets overview, here:
Is this what you mean? If not, can you please clarify? Thanks!
Cheers,