SP 2019 Search: Auto managed properties disappear

Question

I've a problem with our SharePoint 2019. We have a site collection with only site collection fields.

When I run the first full crawl, all our fields are appearing in crawled properties and also the automatically managed properties are created.

After first full crawl I've created some custom managed properties for some crawled text properties (ows_q_TEXT_XXX).

Then I've done another full crawl.

The auto managed properties XXXOWSTEXT disappear from search schema. In my search results pages these fields can be fetched but have null values.

I've tried the suggestion from here to clear the SharePoint config cache but no success: New Managed Properties don't contain values

SharePoint version: 16.0.10375.20000 (2019 PU 2021-06)

Answer 1

Installing SharePoint 2019 (KB5001944) July 2021 update fixed the issue.

Auto managed property disappear from search schema but is searchable and works as expected.

No full crawl or service application recreation required.