Crawled Properties Not Created From Site Columns in Modern Sites

Crawled properties are not being created from Site Columns in Modern Sites when the column is properly implemented. This impacts SharePoint Online only; SharePoint Server 2019 is not impacted. These are the reproduction steps.

1. Create a Modern Team site
2. Create a new site Content Type and new Site Column added to the Content Type
3. Apply the Content Type to a List or Library
4. Add content to the List/Library and populate the custom column with information
5. Request a re-index of the List/Library or Site
6. Search for your crawled property after a period of time (you can wait for 24 hours just to confirm)

If you repeat the process for a classic site template, you should see your crawled property in the search schema in roughly 15 minutes or so. Remember, there is no SLA for search, so even on a classic site it may take quite a bit longer but the crawled property will eventually appear.

I contacted Microsoft Support on this issue and they confirmed that it was a known issue being worked on by the product group with no ETA on a resolution. Instead they provided me a workaround (but would not tell me why it works).

• Navigate to: https://tenantName.sharepoint.com/sites/siteCollectionName/_layouts/15/user.aspx
• Manually add your account to the site collection
• Request a re-index of the Site
• Wait for a period of time and the crawled property should present in the search schema, usually in a few minutes

This workaround does indeed work. I tested this and the crawled property (site column) appeared in the search schema within just a few minutes after requesting the re-index.