Someone else had a similar problem with the Snes9x forwarder when it's launched that way.Um, is it just me or do both DOL and ISO forwarders created by modmii not work when launched through USB Loader GX?
Ah, so you're launching it via a channel forwarder. I was launching it via the loaders built in homebrew browser, which does work.
For years the loader wasn't able to patch WiiWare and VC games, but I fixed that in the new update. I think that fix is what causes this issue though, so I'll need to try to make it handle both games and channel forwarders.
EDIT: I've fixed it for the next release.