SharePoint Online Search Results not returning results for PDF file names

Question

In SharePoint Online, we have a document library of around 200,000 documents with a set of custom columns along with default columns like Name, Title, etc.

Searching files with some text, that is present in the filename, of some PDF files, no search results returned.

I have checked everything, Re-Indexed the Document Library, then Re-Indexed the whole site, wiatited for 4 hours, but it is still not returning results for PDF files. If we search for text on file names of other file types (msg, docx, xlsx etc.), results are returned, as expected. Only PDFs are having this issue. I am a site collection administrator; therefore, it should not be the permission issue

PDFs are not images but actual text PDFs we are just searching for text in the File Name field so it should return at least by matching file name.

Example 1 (PDF File)

PDF File Name: 45062-Customer Joe Blog.pdf

Search Query: 45062

Search Result: No Results

Example 2 (Docx File)

Word File Name: 45876-Customer Joe Blog.docx

Search Query: 45876

Search Result: 45876-Customer Joe Blog.docx (as expected)

Answer 1

Check as follows:

1. Confirm if the content is searchable via different search criteria, search with ".pdf" to compare the result.
2. Verify that the document is a Major published version.
3. Verify that it is within supported limits and boundaries: https://docs.microsoft.com/en-us/sharepoint/search-limits?redirectSourcePath=%252fen-us%252farticle%252fSearch-limits-for-SharePoint-Online-7C06E9ED-98B6-4304-A900-14773A8FA32F

We recommend opening a support case if content is not being reflected as expected in search within 24 hours.

Reference:

https://techcommunity.microsoft.com/t5/microsoft-sharepoint-blog/introduction-to-sharepoint-online-search/ba-p/170708