I wanted WiX to remove the AppData folder when uninstalling, so I looked at RemoveFolderEx and followed a few posts/guides on how to get it working. As far as i can tell, m
Use a different Id for the Property than the Directory. They're clashing, which causes the property to be empty when RemovedFoldersEx tries to process it.
In your logs, above the 'Error 0x80070057: Missing folder property: PRIVATEDATAFOLDER' is there a log line such as 'Ignoring disallowed property PRIVATEDATAFOLDER' and if so, have you tried adding 'secure="yes"' to your PRIVATEDATAFOLDER property?