Hmm, I don’t even know what else to suggest then. It is possible that the host/device mode switch itself is faulty, or some other fault on the display board.
I decided not to use the “device” mode at all, since it’s just inconvenient when the display is connected to the computer via an adapter. Switching the USB cable from the adapter to the display every time, or connecting the display with another USB cable – I don’t like this idea. It’s easier to stick a flash drive into the display and wait a few seconds until the display updates the project from it 🙂