I'm having a similar issue - the logs show (end of URL redacted to hide any user key/token) :
[2018-07-04 @ 10:45:35.448] [butler] butler stderr: bailing out: htfs.Open (initial request): Get https://w3g3a5v6.ssl.hwcdn.net/upload2/game/xxxxxxxxxxx: http: server gave HTTP response to HTTPS client
[2018-07-04 @ 10:45:35.449] [butler] butler error: htfs.Open (initial request): Get https://w3g3a5v6.ssl.hwcdn.net/upload2/game/xxxxxxxxxxxx: http: server gave HTTP response to HTTPS client