Most times when I load my Wii U while I have my USB of wii wbfs, it will freeze the console on startup. The only thing I have on the USB is the wbfs folder which contains the 2 wii games. I have also tried deleting the contents of the USB so that is has nothing on there. It will still freeze. The USB is 64gb and FAT32 formatted. I have also tried using different USBs and USB ports.
Steps to reproduce
1 - Insert a FAT32 USB into the Wii U.
2 - Turn on the Wii U
3 - it should freeze on the screen shown in the image with no sound or movement.