It might be a CORS issue.
The host needs to allow ajax requests from external domains (such as project preview from construct.net) to reply.
Try to see if it works if you export your project and upload/host it on the same domain website (potato-time.jp). This will bypass any CORS problem.
Otherwise, if you have admin access to the server or host, you can add
Access-Control-Allow-Origin: *
to the server header to allow ajax requests from any domain on the web.
cors-test.codehappy.dev