First test with an owner or administrator account. If the item appears there but not for a viewer, review the viewer’s library access.
Confirm that the file is inside a folder assigned to the expected library and that the Portico service account can read the complete path. A desktop account seeing a network drive does not prove the service can see it.
Check the current library filters and search terms, then run a scan for that library. Review the scan result for unreadable paths, unsupported files, or matching failures.
When the item appears under the wrong title, fix the filename and use Fix an incorrect match instead of repeatedly adding the folder.