How can I do that? If I right click on a folder in an album and choose Find Duplicates from the context menu, digiKam quickly displays that it found zero duplicates. That folder contains other folders, and duplicates do exist across these subfolders.
Side note: when I right click "Find duplicates" in the Albums list, digiKam should start finding duplicates. Instead it does nothing, and I have to click the Find Duplicates button at the bottom.