Matomo not tracking all downloads of documents

Hi there,

On one of the domains on my account, it seems like Matomo is not accurately tracking number of downloads.

Example page:

This page receives hundreds of visits everyday and we know that many of those visitors download the Word document which is located on the page. However, Matomo has only tracked 3 downloads of the document during the last month or so.

Could you help me troubleshoot what the problem might be here?

Thank you!