A Soft-modded Nintendo Wii with the Homebrew Channel and the latest cIOS installed.The differences will be detailed on this page. There are two different installation methods (automatic or manual), and two different installed channels which will be displayed on your Wii (Full channel or Forwarder). Try a new USB drive, Hard drives are supposed to work the best, flash drives sometimes work, I've found that older flash drives seem to have a better chance of working.This guide will explain how to install USB Loader GX on your Nintendo Wii.

Try a new SD card, sometimes they just go bad.

USB Loader knows the file structure it likes better than anyone else, so it might help to just have it make a new backup that you can try.

Try putting the USB stick in while empty and formatted FAT32 and make a backup of a game in the Wii CD drive.

Again same as 3, make sure to back everything up. You could simply try deleting and recopying a fresh download of USB Loader GX onto the card first but I've found a full reformat makes a big difference. Reformat the SD card to FAT32, use the full/long/overwrite setting instead of the quick one, redownload USB Loader GX and put it on the SD card.I like to take my time on this step to make sure it comes out right. I've found cIOS - Wii Guide by RiiConnect24 explains a good working cIOS configuration. Make sure the cIOSes are in the correct slots and the correct versions.(it sounds like you have already done this so feel free to skip it) I think they have a factory default option. I'm just including what you've done here to try to make the answer as complete as possible in case anyone else needs help in the future. I think you've already tried some of them so skip suggestions 1 and 2 (and any others you have tried). I might suggest the following trouble shooting steps. It usually seems to relate to the settings in USB Loader GX or a corrupted file on the SD card or usb drive. I've had some similar issues with USB Loader GX in the past.

Best usb loader for wii u