Can you verify that when the screen changes from the main menu, to the file list view, that there is a Set Screen Type being sent, and that the destination is your USB UIRT device ?
When the screen changes from the main menu to the file list view I see three commands, a 'Populate Datagrid' and 2x 'Get Datagrid Contents'. No Set Screen Type command appears to be sent. I'm tailing DCERouter.log for this info.
This would explain why the ch+/- button commands are being sent to the Media Plugin rather than the Orbiter? While playing media my media control buttons are not working either, I assume a similar 'Set Screen Type' command is missing there.
This is pretty critical to proper operation by IR remote, I'm going to create a ticket.