Buddy Press Docs – when upload a doc, it is “not found” but still exists

We have a closed community where Buddy Press Docs are the document handling system for the boat club.

When I created a new document (post) and added the document (attachment) the attachment procedure was really fast and it was seemingly added to the buddy press document. However, when we click on the document it is a page with “File not found” instead of the document.

When I check the library, sure the document that is linked to this post is not there (wp issue?) so I delete it and add a new attachment (same procedure). However, this document is also not found.

I do this five times over, and finally I have five uploaded documents and no working attachment links. In the library only two out of five uploaded documents actually works, so I copy the url of these and paste into the document text of Buddy Press Doc instead.

But what happened? How can I avoid this? It was regular pdf’s under 100mb.

The page I need help with: [log in to see the link]