Get articles call does not include latest label updates

I'm using cursor-based pagination for getting all the articles.

GET / api / v2 / help_center / articles? locale = en-us& page [size] = 100.

In the result, I have the articles, but some of the labels are missing.

My observations:

1) Labels are not included if you added them and save the article without editing the text of the article. I assume that it is not updating because the Publication status is not changing. Am I right?

2) If you edited labels of the article and edited text of the article that labels are returned correctly but if the call is made approx. in 1 hour later. Why do we have such a delay here?

However, when I'm using

GET /api/v2/help_center/articles/search.json?label_names=label1

it returns an valid article with newly updated article.

Could someone explain the logic behind this?