EXCEPT function in Narrative Report no working

Summary:

Use of Except function in a narrative report not functioning as expected

Content (required):

I have an account SDUKS_SC that I wish to pull in a narrative report as a single line (with the option to zoom) but I want to exclude one of it's child accounts and its descendants: SDUKS_TK.

Note that these are not shared members.

In the Narrative Report I've used the Except function as follows (first parameter is the account to exclude, second parameter being the account to exclude it from)

When I preview the report, what appears in the row is the account balance I wish to exclude, i.e. balance on account SDUKS_TK