Accelerate Mobile Pages (AMP) Real Time Config(RTC) Setup

Question

I am trying to set up AMP RTC for header bidding on my site. I am using 3 vendors(IndexExchange, Rubicon, and Amazon APS) plus Google Adx as my ad server. Setup was easy, but I am only able to get 2 (APS and Adx) out of 4 vendors to bid. I have scoured the web for a setup guide for Rubicon and could not find any, not even on their own website. Index Exchange has a guide that I have followed to the T but it is not working either.

Sample code for one of my Ad units:

<amp-ad width=336 height=280
 type="doubleclick"
 data-slot="/xxxxxxxxx/Amp-in-Content-1"
 data-multi-size="320x100,320x50,300x600,300x250,300x50"
 rtc-config='{
  "vendors": {
    "indexexchange": {"SITE_ID": "xxxxxx"},
    "rubicon": {"ACCOUNT_ID": "xxxxx", "SITE_ID": "xxxxx", "ZONE_ID": "xxxxxx"},
    "aps": {"PUB_ID": "600", "PUB_UUID": "xxxxxxx-xxxx-xxxx-xxxx-xxxxxx", "PARAMS":{"amp":"1"}}
  },
  "timeoutMillis": 1000}'>
</amp-ad>

under this config only Amazon APS and Google AdX work

Things I have tried: -I have tried testing rubicon without RTC and the adds were showing. under this config only rubicon ads shows since there is no biding taking place:

  <amp-ad width="336" height="280"
      type="rubicon"
      data-method="smartTag"
      data-account="22616"
      data-site="340422"
      data-zone="1794016"
      data-size="43">
  </amp-ad>

I have tried changing the vendor endpoint from lowercase to camelcase. For example, I changed 'indexexchange' to: "IndexExchange": {"SITE_ID": "xxxxxx"}, this is because the example of the IX page uses camelcase despite the AMP page explicitly stating that it has to be lower case. I tried both for good measure, neither worked.

If anyone has experience implementing AMP RTC and can tell me if there is something wrong with my code I would greatly appreciate it.