Description field needs to match exactly what is shown within the General tab if you inspect properties on a file. It is not a generic field which you can label your exclusions.
If you right click, select properties then move to the General tab you will see
I don't recall if this is case sensitive but it would not surprise me to find out that it is.
I have seen in the past where the file creator has padded the description with a space before/after, probably unintentionally but it still impacted my exclusions.
Hope this helps.