USB Host CDC-ACM with USB peripheral in custom mode

I have a custom board that I'm trying to get a Host CDC-ACM stack working on the USBHS peripheral.  Because of the board connections, we are running the USBHS peripheral in Custom mode.  We have signals attached to the OVRCURB. VBUS and ID ports, and "None" on the others.

I have made the Device version of the CDC-ACM work with the USBHS peripheral in this configuration, but when I switch to the Host version (and making the appropriate code changes), it's not working.  I never see the host event callback get called.  I've set a  breakpoint in the ux_system_host_change_function in the generated common_data.c file, and that's never hit either.  I've tried delaying the call to the ux_common_init0 routine until the USB cable is detected, but that doesn't seem to make a difference either.

Is there some condition that I need to generate or routine to call to get the Host code to initialize when I am running the USBHS peripheral in custom mode?