User Search Doesn't Work

I'm running Spark 4, PHP 7.1.1.

When I do a user search with a clean spark install, no users ever match even though I would expect several to do so.

I walked through it a bit, and I think the problem is in the Laravel\Spark\Http\Controllers\Kiosk\SearchController.

performBasicSearch doesn't seem to properly interpret the $request param as a Request object.

Here is a code snippet from inside performBasicSearch after doing a user search for 't'...

Log::debug($request); 
// returns array (
//  '{"query":"t","errors":{"errors":{}},"busy":false,"successful":false}' => '',
// )

Log::debug($request->input());
// returns array (
//  '{"query":"t","errors":{"errors":{}},"busy":false,"successful":false}' => '',
// )

Log::debug($request->input('query'));
// returns nothing

Any idea what's causing this problem? I see that $request is an array that contains a json string. But there is seemingly no way to manipulate/access that string?