If you upload a world with special characters, such as '+', the upload will fail. Trying to load into one of these worlds will cause you to instantly go back to your home world.
The world has been fixed now, but this was the error in the log:
Log message:
[Log:6/8/2018 9:38:02 PM] [656] Request [https://api.vrchat.cloud/api/1/file/file_fadacf29-1ffc-4f14-99cd-8151f70a89e3/1/file] finished Successfully, but the server sent an error. Status Code: 403-Forbidden Message: <?xml version="1.0" encoding="UTF-8"?>
<Error><Code>AccessDenied</Code><Message>Access Denied</Message><RequestId>D0CF5E25B6B42080</RequestId><HostId>s1JSLo3giiwz8axgtG5XaAxhe4+uJA2ewcoBlGUNsCM6tF2H8MV4XYQwnAe8bSlmAQktkswiEsU=</HostId></Error>
[Log:6/8/2018 9:38:02 PM] Error Downloading or Instantiating Custom Scene - https://api.vrchat.cloud/api/1/file/file_fadacf29-1ffc-4f14-99cd-8151f70a89e3/1/file - ServerReturnedError
[Error:6/8/2018 9:38:02 PM] Downloading the room failed.