From the release notes:
Workflows
I'm not able to work out what actually changed...
When you open from a workflow, does 8.3 filter the Notes Tool to just that workbook? I wonder if that is the change.
does 8.3 filter the Notes Tool to just that workbook?
Does 8.4 do so for you (not happening for me on Mac)?
Yes, but only when the Notes tool isn't already open. When the tool is already open, it just switches me to that note but leaves the filter as it is. (With the side effect that if the note you're opening is excluded from the filter, then you can see the body of the note, but not the summary in the middle column.)