Which version of Kibana were you using while making the tutorial?
I'm on Kibana 7.3.2 and I get following error Cannot parse '(NOT watcherState.keyword:processed) AND ()': Encountered " ")" ") "" at line 1, column 42. when trying to get saved query data.
I wonder if the syntax of "savedSearchId": "search:b7c6a9c0-xxxx-yyyy-zzzz-b968b65e520a", in metadata differs across Kibana versions.