Crawled properties not appearing under Search schema for Site columns

Question

I have created couple of site columns using PowerShell (CSOM) script in SP online site. I have added all these columns to libraries using PowerShell (CSOM). Later I have migrated hundreds of documents to different libraries which contains these site columns.

I want to implement search refiners. So I wanted to add few of the created site columns to RefinableString properties. When I am trying to add the crawled properties to the Refinablestrings, I am not able to identify crawled properties for created site columns.

I have created site columns two days before and migrated data 24hrs ago. I think this time is sufficient for crawling.

Am I doing something wrong here?

Answer 1

If these are Modern Team sites, this is a known bug. Not only do you need to add the column to a List/Library and populate that column with a value on a single List Item/Document, you must also add a user to a SharePoint group. At that point, perform a reindex on the List/Library or Site.

See Crawled Properties Not Created From Site Columns in Modern Sites.

Answer 2

I'd wait a bit longer. It's not unusual for crawled properties to not populate within 24 hours, and only columns that contain data will be indexed, so your empty site columns would not have gotten indexed.