both MBR and GPT are fine and detected by USBLoaderGX. though, I found a bug in GPT last week, anyone reading this : don't dump disc to GPT using USBloaderGX until next revision (1273).
do not try to "convert" the mode of your HDD, it could go wrong and you lose your data, while it's not the problem of the drive.
plus, if HBC see the drive then it's currently using MBR.
That's really strange that it's seen as Toshiba drive!
Maybe the device is really a Toshiba, and only the "packaging" is Werstern digital?
And, we still don't have any clue about partitions themselves. you could have screenshot your device management for example if you didn't know what to report.
but I just wanted to see which partition type you had, if the Wii games are on the first or second one, etc.
all you told me is you put your games on the partition you called (in windows) "wii hdd". very informative.