Oh no! If it's any consolation, I think it might be the site itself, not the search plugin... the site has been acting up in unrelated ways. The site desperately needs a rewrite, but I didn't have time before this launch date.
Apologies for this! Someone's very kindly put up a PR[0] that I suspect will fix this, but it's past my bedtime so I won't get a chance to review/merge/relaunch it until tomorrow.