I'm helping to design a website using Algolia Instant Search. There are several facets that the user can modify to return a set of data that they can browse through. The Instant Search behavior is such that if a certain facet is no longer modifiable, it is removed from the layout. An example would be if the user narrows everything down to one result, then the "Number of Staff" range refinement would disappear, because the single result has only one "number of staff".
Some users in testing were confused by the disappearance of facets in response to other facets being modified, so we changed the layout to leave the facet header and a message: "no refinement available." This seemed fine until the latest round of changes, where the client wants us to make modifications the lessen the amount of space that the facets take up on the screen. We've moved to a drop-down model like on Trulia, where you click to expand the facet selection and do your selections in the dropdown.
Now the problem is that users may click and then be frustrated when they are faced with the "no refinement available" message. There is a "facet summary" section where the current state of the facets are reported, so they could see there that the "range" is just one value now. I'm wondering if this is enough and we should just go back to removing facets entirely?
I've seen examples where non-applicable facets are just removed (e.g., eBay does this) but since this previously confused some users, I'm hesitant to do this.