The purpose of the USB port on the side of the Go Travel Keyboard is for convenience to plug in low power USB devices such as a memory stick, mouse, or other low-powered USB device. Plugging devices into the GO keyboard other than very low power devices like a USB memory stick causes power consumption in excess of the power available via a USB port (5VA). This is a USB power limitation, not a specific limitation of the device.
USB ports have limited power available so when you plug in or chain two higher power devices to a single USB Port, you will exceed the available power of your computer’s USB port which will generally cause both devices to malfunction or fail.
General rule of thumb is to always plug your keyboard directly into your computer’s USB port and limit the types of devices that you plug into the Go.