Have you upgraded to the new .mdc file format? I didn't get around to .cursorrules before this format came out, but I'm finding .mdc is reliable if configured well (e.g. with the right file extensions)
My understanding of the docs is that these are all handled the same: Cursor just adds any rules file to the context for each request, and that's it. I don't believe there is any mechanism by which to call special attention to particular rules in the context window. I could try renaming the file though.