Ok, here's one I've never figured out...
I'm using Search API to handle fairly basic, non-faceted search requirements on a small site. When I navigate straight to the results view page or search for an empty string, the default results are the entire indexed content. This is understandable as it's essentially just an unfiltered view, however, it's not really what you'd expect from a search UI.
I've messed about with views contextual filters in every way I can think of and I just can't get the default to show the Views "no results" value. I have it working in Views preview but not in actual practice - likely because the args are not as you'd expect when using Search API full text search via an exposed filter.
Can anyone shed any light on this?