The use of the term extracted is not a good one. The schematic editor will do an
"extract" when it checks and saves. The datestamp set by check and save is compared to the last modified datestamp in the editor. If modification is after extraction you get that message.
That message can be even odder and more confusing when netlisting an
extracted view. Since the extracted view is structurally the same as a
schematic view, just without the interconnect lines being drawn, the same
netlisting code is used. If you manually edit the extracted view, the
lastSchematicExtraction property needs to be set. I don't recall how you
keep the last modified time from being changed by the setting of the
lastSchematicExtraction.
Hope this helps you