Sounds like it may be stuck in cache. I'd clear your cache and see if it goes away.
UNSOLVED Is "usage" tag in "/admin/manage/uploads" deleted? Or how to make it work?
There are some files in the
\assets\uploads\folder whose topic and replies have been delete.
I have to delete them to realize space for other files. But I don't want to delete some under-using assets.
So is there some other ways to manage assets of my nodebb?
There is a filter for unlinked assets that nothing is using. If it is not under there, it is in use somewhere.