UMH-21 with USB-HUB4

I have a M-Audio keyboard plugged into the USB HOST port on the UMH-21 and it is working ok. However, when connected through the USB-HUB4 it no longer works. There is no other device plugged into the hub.

The UMH-21 has been upgraded to firmware version 2.3.4. All other functionality seems to be working.