Dear Sumo-ling!
Susie stepping in for Gor.

Let me address your questions. :)

1) The license issue: may I know if it's possible the following happened:
-You activated the Gold version and then installed the zip of the Gold one.
-Stacked the code, activated the Platinum plan and tried to login to the BackupGuard Gold from within the plugin?

If this is what happened, then please, download the zip of the Platinum plan and the try logging in. There should be no issues when this is done.

2) Another Sumo-ling mentioned the temporary solution which is disabling the option called Block proxy HTTP headers from the Firewall section of the security plugin. You can try that one while we're looking for a more steady and permanent solution for this.

I also noticed that you mentioned you didn't get a message from the support team. We double checked every chat we've received and all of the conversations were replied to.
May I ask you to:
1) Check the spam/junk folder of your mailbox,
2) If you cannot find the email from us, please, try contacting us again from the same email address previously used so we can investigate why the messages weren't received.

P.S. A special thanks to the Sumo-ling on sharing the temporary solution of disabling the Firewall option. :)