I see.
If you set \Unwanted\ in the exclude filter, you will get the results that you want.
The points are two.
1. If you want to specify as directory in the filter, it requires \ character to the end of path.
2. If you want to specify only to affect top-child-directory, it requires \ character to the top of path.
(If you set Unwanted\ (not \Unwanted\) in the exclude filter, all Unwanted directories will be excluded.
For example, D:\Unwanted\, D:\subdir\Unwanted\, and more)