Page analysis does not work on page properties first load

[sxp-dalibor]

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Please give us a description of what happened.

We started having issues with page analysis indicators after upgrading from typo3 v12 to typo3 v13.
When you first open page properties and click the SEO tab:

Progress bars:

• Progress bar of seo_title is not evaluated
• Progress bar of description is not evaluated

Page analysis:

• Readability analysis reports "not enough content" even though there are about 800 words on the page
• Problem: "Meta description length: No meta description has been specified." is reported even though the description field is filled
• Problem: "Text length: The text contains 0 words." is reported even though there are about 800 words on the page
• Problem: "SEO title width: Please create an SEO title." is reported even though the seo_title field is filled

Please describe what you expected to happen and why.

Progress bars:
Both progress bars only appear once we start typing into the seo_title, resp. description fields.
It seems like the javascript which triggers the progress bar rendering is only not triggered on the first page properties editor load.

Page analysis:
Analysis of seo_title, resp. description fields seems to have similar issue as the progress bars - it is probably not triggered on the first page properties editor load. Once we force the re-run of the analysis, e.g. by clicking the "This is cornerstone content", the problems reported before are gone.
Analysis of the page content is still reporting 0 words even after re-run, but this might be related to the headless plugin which we use for frontend rendering into JSON instead of HTML.

How can we reproduce this behavior?

1. Open page properties backend editor of a content page
2. Open SEO tab
3. Javascript of progress bar & page analysis are not triggered

Screenshots

On first page load:

After typing into seo_title & description fields & clicking cornerstone checkbox to trigger new page analysis:

Logs

• No logs as this happens in JavaScript

Additional context

Add any other context about the problem here.

Technical info

• TYPO3 version: 13.4.0
• Yoast SEO version: 10.0.0
• Relevant extensions in case of a bug: headless