Cannot Apply Sensitivity Label to PDF File No Encryption Present

Hi all,

I am facing an issue when trying to apply a sensitivity label to a PDF file stored in SharePoint. The error message I get is:

Error: Sensitivity label cannot be applied at this time due to the nature of file's encryption.

However, I can open the PDF file normally, and it does not seem to be password-protected in any way.

Has anyone encountered this before? Is there a way to apply a sensitivity label to such files?

Any guidance would be greatly appreciated!

Thanks in advance.