AMP-Ads can not reach 100% Viewability

### 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_