Hmm I would still expect it to give the 400 error in a scenario where a invalid Client ID is provided or none at all, so I think it’s weird that you are seeing a different outcome (as in, no errors populated.) Though, I could be misinterpreting (or misunderstanding) something with AJAX due to my limited knowledge on it 
It may be a remnant of the server issues - as I still see zero results returned for this one (even with other games).