There seems to be two things going on at the same time:

Every time any of the cabin crew finds an item they move heaven and earth to ensure you get your items back. I have left anything from a jacket to an iPad and in both cases someone was running after me all the way to immigration. That's an outstanding attitude and a real life and time saver.

Once the cleaning team takes over however, items seem to mysteriously disappear. While it did not happen to me, I had two frequent flyer friends telling me that they left something on the plane and despite filing a report nothing could be found. My only conclusion is that cleaning crews are very quick to discard things (as in: throw away) as they are under huge time pressure to get an aircraft turned around and they are not paid for completing all the paperwork necessary to get an item to lost and found.