Remove 'invisible' character through selected documents

I have a folder with many documents that need a particular character string with line-return – “xx/” – removed throughout. (I am ‘looking at’ the several documents in Scrivener mode.)
I have copy pasted the string-with-return to the Find dialog and left the Replace box empty: Alt-A/Replace All does not remove the string-with-return. (I want the string’s entire line gone.)

Replace & Find works as expected in only the one document where the cursor sits; Replace All with the Replace All Scope to Entire File (leaving the Find/Replace values as they were) makes no changes, gives no result’s feedback, only the button’s depression.

(I read in another post about ‘Show Invisibles’, then copy/pasting the return to Find … , but that did not work for me.)

[Scrivener, trial version for Windows (7); I’m waiting for v2.0/Windows before buying, waiting for the dynamic document name feature.]

So, it seems that I cannot merely copy “xx” and the immediately trailing return (hard or soft).
Reading another thread that asked a similar question – copying text and its (italic) format – I saw that Find/Replace may only be for simple text, that complications like formatting (and line returns?) are not visible to the routine?

Right, the Find/Replace function is purely the text; it doesn’t replace (or make any distinction between) formatted text. Carriage returns are a separate issue. They aren’t currently supported in the Find/Replace, but that support will be added in the future.

Find/Replace does work through multiple documents in a Scrivenings session, with the scope set to “Entire File”. The problem here was just that the particular search term wasn’t valid.