definitely not the usb port as I was just running wii games from the same hard drive thru usb loader gx. It's definitely something Nintendont doesn't like as it also happens from the HBC (v1.1.2, I just checked to be sure it wasn't that HBC was too old, too). UGH! giving up for now as I need sleep.
NEW: Last version I had working was 4.441, I just found my files from when I did the Wii U CFW mod back in 2017. Prior to that was v3.331 from when I did the vWii mod originally. Not that that helps I bet, but I just don't get what's going on. Neither of those behave any differently now, they both hang the same way - I'm about ready to dig up another Wii U to mod just for this...