AMP-Ads can not reach 100% Viewability

[Pubstream]

Description

Every AMP ad has a viewability tracking issue. They only track up to 50% but never 100%. The reflective attribute "mtos" always transports "0,0,1009,1009,1009" regardless of whether the image was 100% in the viewport or not.

This only happens with AMP ads (id=ampim), the regular (id=lidar2) ads reach 100% viewability

Reproduction Steps

1. Open the Chrome developer toolbar, "Network" tab.
2. Go to the AMP Ad demo page https://amp.dev/documentation/examples/advertising-analytics/amphtml_ads_vs_non_amp_ads/
3. Scroll to the AMPHTML Display section
4. Look at Network tab for ActiveView ping https://pagead2.googlesyndication.com/pcs/activeview
5. We now see an incorrect MTOS value (0,0,1006,1006,1006
6. Scroll to Regular View
7. Check the network tab for ActiveView again
8. We now see a valid MTOS value (1009,957,51,331,65).

We would also expect 100% for AMP advertising.

This visibility problem occurs everywhere, not just on the demo site!

Relevant Logs

No response

Browser(s) Affected

Chrome

OS(s) Affected

Mac and Windows

Device(s) Affected

No response

AMP Version Affected

No response