I have a custom board that is very similar to the PK-S5D9 that utilizes the USB Host mass storage.
The VBUS is controlled with a different IC that is active high instead of active low (on the S5D9).
Does the VBUSEN pin need to be controlled manually or is it controlled in the driver code?
I have also used the PK-S5D9 board to verify that the VBUSEN line does not ever go high, even when I select "Active High" under the setting "VBUSEN pin Signal Logic".