This seems to be a firmware malfunction. Something that survives a factory reset. Normally everything gets cleared except the contents of data/media incl emulated_sd. Formatting the data partition should result in bricking. I had achieved that once, on another device. Restoring the stock recovery and flashing stock rom brought it back to operational. But then you have a really virginal device, except for the Knox flag.
There is a mechanism for operation on a 500mA usb2 port, that puts the Note in charging mode, once it enters standby, otherwise it allows data transmission w/o drawing any power. This seems to have sort of reverted.