Incomplete Search Results in SharePoint online

[PicardWinery]

I've inherited a site and a subsite with multiple document libraries.  One of the document libraries contains ~1.4 million items (folders and documents). The large document library is sub-divided into folders and sub-folders, so there are ~3,000 to 5,000 sub-folders in each folder.

The users rely on the search function of the document library to find items within document library, but the results appear to be incomplete. The field that they are searching against is the built in "name" field of the built in "folder" content type.

I have re-indexed of one of the document libraries, but it has not improved the issue.

How can I combat this issue?

I can't find the "name" field in the site's search settings, so i'm not certain that I can change any settings related to the field. It is one of the default SharePoint fields, populated when a user creates a new folder and they name the folder.

[#2]

Hello @PicardWinery 

which search do you use, default Microsoft Search or PnP Modern Search Web Parts?

That's right, it's default column and there will be indexed automatically. You can not set anything others.

With less documents it works fine in my test ;).

I have see in my Tenant it's a default crawled property ows_LinkFilename, you can try to map the Crawled Property to a new Managed Property and activate the option searchable.

It's not possible to set more or do an index reset. Maybe you can create an MS Ticket.

Best, Dave

[#3]

Thanks for the response - after initiating a crawl it might have resolved itself. There are quite a few more results now.

We are simply using the search function that is built into every modern SharePoint Online site!

I just wanted to be certain that I wasn't missing anything before I talked to MS. I read the MS articles about SPOnline search, and it appears that re-crawling is the only option to correct this type of issue. Also, since the field they're searching against is a default built-in, I wanted to be certain that someone didn't exclude it from the crawl somehow.

Thank you!