I prepared a bunch of Feature Layers and a Web Map in the My Content/Home folder, and then selected them all and clicked Move -> FolderA. The Web Map and one of the Feature Layers moved successfully. But four of the Feature Layers will not move. I get the error above (screen shot attached).
I don't know what it means, or why the other Feature Layer moved successfully. I have confirmed that the Feature Layers are not shared, and do not already exist in the destination folder. They also are exactly the same (except for the data itself) as the Feature Layer which moved successfully. What am I missing?