keep empty categories

[Stevef48]

I've set "keep empty categories" to No, but empty categories aren't removed when I right-click on @Keywords and choose Refresh Data (Shift-F5), or Refresh All data driven categories (Ctrl Shift F5).
What am I doing wrong?
Thanks in advance,
Steve

iMatch 2021.16.2

[Mario]

Works here just fine.
Switch @Keywords to not keep empty.
Remove a keyword used 2x from the corresponding files.
Refresh @Keywords.
All empty child-categories are removed.

Add a new keyword to a file.
Keyword shows up below @Keywords.
Remove keyword from file.
Category is removed too.