Amp-Audio lost tracking icon between last release and this Beta.

### Description

When comparing 2307150128000 vs 2307212240000 on a page with amp-audio present, I noticed the position indicator was missing in the Beta Release candidate.

The attached screenshot shows the regular release on the left, and the beta version on the right.

### Reproduction Steps

Using Chrome 115 Device Emulator.
Ensure your intended version of Amp is active over here:
https://cdn.ampproject.org/experiments.html

I used this URL to verify:
https://amp.closetfactory.com/blog/closet-factory-made-ashley-hafstead-closet-space-fit-queen/

You might need to scroll down, but maybe not as the amp-audio element is near the top.

Play the audio
Use the middle element to jump forward some minutes
Pause the audio.
Observe the element.

### Relevant Logs

_No response_

### Browser(s) Affected

Chrome

### OS(s) Affected

_No response_

### Device(s) Affected

_No response_

### AMP Version Affected

2307212240000