Yes, the macro is designed to work on a single line of unselected text.
This is because in the rest of the situations we have the right-click -> Convert Selection > Comment/Uncomment functionality or you can pull these two buttons onto the toolbar.
Agin, the latter just does not work for a single un-highlighted line of code – hence the macro.
I must add, this creates some uncomfort for me – split, non-unified functionality :hammer: .
Hope Yutaka is listening: I suggest a change to allow commenting code regardless of whether a line is highlighted/selected.