Apple - Support - Discussions - Retouch/Clone problem ...: "I can't get Retouch (or clone) to do anything at all. They act like they're working but nothing in the image is changed. However the Spot and Patch tool will work on these images/files."I'm using 10.4, but it sounds like this is a bug everywhere.
Update 3/22: I exported as PNG and reimported and the tool works, so it's not broken for every file format. Then I found the "limit to 1024" PNG export is broken -- it ignores crops. Apple must punish the QA group for finding bugs.