If the 0% refers to free disk space then the disk is full, so probably a corrupt index/FAT so initialising may fix it if there are no hardware errors like bad sectors. If it happens again then you may have to prep/format the disk which will take some time, I think there is a Vix menu option somewhere, probably in the Viz sub menu.
VU+ Uno 4K SE Twin FBC Tuner 1TB HDD - Magic-FHD skin
TV - LG OLED55CS6LA
Remote - Logitech Harmony One
Update from me, I did a full scan with testdisk and it took about 8 days on my 2tb disk. It recovered a list of filesystems but each one was corrupt and so it could not be loaded. The disk itself seems ok and passes diskcheck without errors. So I ahve lost my data. It sounds like Vix cannot programtically do this so I can only presume the disk itself has an issue. I'm still going to use the disk but backup anything I want to keep and see how it goes.
I don't think Vix can do a low-level format, it only seems to do an initialize which clears the FATs or whatever the equivalent is in the linux file system. Personally I would not trust the disk, I would install a replacement disk and format the replaced disk appropriately.
VU+ Uno 4K SE Twin FBC Tuner 1TB HDD - Magic-FHD skin
TV - LG OLED55CS6LA
Remote - Logitech Harmony One