Upgrade to 3.0 causing weird behavior - first entry has response but no request?

We upgraded our private instances:
WPT 3.0
Agent 3.6.2
We currently host on Amazon (AWS).

We are seeing that the first line of waterfall has no request, and a response that occurs much later than the actual page. Anyone see this? The response seems to indicate a possible P3P issue?

Error/Status Code: 200
Protocol: HTTP/2
HTTP/2 Stream: 1
Client Port: 61647
Request Start: 0.243 s
Time to First Byte: 0 ms
Content Download: 0 ms
Bytes In (downloaded): 0.4 KB
Bytes Out (uploaded): 0 B


:status: 200
content-type: text/html; charset=UTF-8
strict-transport-security: max-age=86400
p3p: CP=“This is not a P3P policy! See P3P and Google's cookies - Google Account Help for more info.”
content-encoding: gzip
date: Sun, 05 Mar 2017 13:06:51 GMT
server: gws
cache-control: private
x-xss-protection: 1; mode=block
x-frame-options: SAMEORIGIN
expires: Sun, 05 Mar 2017 13:06:51 GMT
set-cookie: NID=98=(REMOVED for security reasons) expires=Mon, 04-Sep-2017 13:06:51 GMT; path=/; domain=.google.com; HttpOnly
alt-svc: quic=“:443”; ma=2592000; v=“36,35,34”

See attached waterfall

It’s probably an HTTP/2 request that has been PUSHed by the server

It turns out both my issues were related to some prewarming functionality in WPT for certain caches. Likely why we only saw it in our 3G tests. It sounds like a race was lost and so we see the response late. Patrick has, most awesomely, provided a patch