I think I'm on my way to fixing it. If I load usbloader gx with another usb drive like a flash drive first, go back to homebrew channel and reload usb loader gx my main drive will load 50% of the time. I don't think my hard drive is spinning up fast enough. My hard drive is a My Book Essential...
I just tried what you said cyan and it's giving me the same issues. This hard drive works perfectly fine on my normal wii. I think that my hard drive could be the problem but why does it only detect it about 10% of the time? Also wiiflow can't detect it and cfg usb loader also crashes.
I just have one drive connected, a western digital 2tb usb 3.0. I have tried the other usb port, similar results. Now it seems very random whether it will crash or not. I just ran Resident Evil 4.
I installed the homebrew channel and d2x v10 vwii beta 53. USB loader GX keeps freezing at the initialize usb drive screen. The only thing that seems to fix it is deleting the config files. I made a nand backup. I'm using wii u system 5.1.2. Should I install ios 236?