Click the file link in the search result page, pop out "404 NOT FOUND"

We use SharePoint Online to create a Communication Site.

When we search the site, it works and comes back a search result page.

But when we click the file link in the search result page, the pop out page shows "404 NOT FOUND".

We found it only happens if the files are in the Documents(Document Library).
if the files are in the other folders(Document Library), we click the file link in the search result page, it succeed to show the preview of the file (in pop out page).

I tried to search this situation but can't any tips.

Hope someone here can help.

Thanks.