is compatible with Stealth drives now for a long time. you need to update nintendont
2)Ustealth works like that :
The HDD has a partition table, this is a place (at the start of the HDD, sector 0) where there are information about 4 possible partitions (size and location on the drive).
That partition table is not always present, the drive can be "raw" or unformatted. the sector 0 exist, but doesn't have any information about existing partitions.
to detect if the table is present on sector 0, there is by convention a "Signature" at the end of sector 0, coded on 2 bytes, with the value "55AA".
The WiiU is not using partition, and format ALL the drive in WiiU HDD format. The partition table being useless to wiiU, the console is using this signature to detect if the drive is already formated to WiiU format, or still has a partition table and FAT/NTFS/Etc. partition on it.
What Ustealth program is doing is simply modifying the signature (not the partition info located on that table), replacing "AA" to "AB".
the wiiU, the computer, anything which check the partition table signature don't find "55AA", so it consider the drive as "not formatted".
Windows tell you to format it, while the WiiU stop telling you to format it ! (one way or another, something tells you it's not formatted)
If you want to put it and edit its content on your computer, you need to "un-Stealth" it first.
Stealthing/unstealthing can be done on a computer, or directly on the console (there is a homebrew capable of doing it)
Ustealth is used to prevent the message on your WiiU menu when a vWii HDD (with partition table) is connected.
Few Wii homebrew have been updated to accept both 55AA and 55AB as "legit" signature for the partition table signature, and check the partition info without issue (location and size of the 4 possible partitions on that drive).
Your issue with emuNAND and d2x v10 is that this cIOS does not accept edited signature (55AB).
But a modified version of cIOS d2x v10 exists, and you can use it instead of the official d2x v10.
That modified version of d2x only helps you with stuff used by d2x !
installing d2x doesn't make ALL the old homebrew work with stealth drives.
it's only allowing you to play emuNAND on a stealth drive.
d2x is used for EmuNAND, d2x needed an update to make emuNAND compatible with Stealth;
Nintendont is used for gamecube games, nintendont needed an update to play gamecube games from a stealth drives;