FCP isn't deleting original media files when I trash clips in my browser

I'm trying to permanently delete some files that I'm not using anymore, but FCP doesn't seem to wanna delete the original media files themselves. Usually when I select a clip in the browser and click "Move to Trash", a window pops up and asks me if I'm sure, but when I do it now, I get no pop up and the clip just immediately disappears from the browser while the original media file remains on my drive in the Original Media folder. What might be causing this?

FCP only moves media files to the trash if they’re stored inside the library, and of course only after all instances of the clip are removed from the library, both in the projects and in the browser.

Well the files I'm trying to delete are definitely stored inside the library, and I'm unable to find any instances of the clips in any of my projects. Also, in the past, when I've attempted to delete clips that were unknowingly still being used in a project, a window would pop up notifying me that FCP was unable to delete the media because of this. Now, however, I'm not getting any sort of notifications whatsoever. The clip just instantly disappears from the browser.