This means the format itself failed. You don't even see an MBR, right (and you know what that is and where to find it)? It is pretty strange wiping the card would work, but not formatting. I can provide a test build within an hour or so, but first make 100% sure the error is not on your side. You could, for example, use GodMode9 to check if you can browse this SD card.
when I format with windows builti-in formatter (fat32 | 4096 byte Allocation unit size), Godmode9 can read the card just fine and A9LH runs fine also.
as soon as I do any kind of formatting in EmuNAND9, all data, incluidng is wiped from 0x0 to 0x240000 (which includes the MBR).
the rest of the data is probably leftovers of stuff that was on the SD card before it was wiped (arm9loaderhax.bin, the key bin files, firmware.bin, firmware90.bin, and the payloads).
the above also happens with the SD association formatter, which I think formats as FAT instead of FAT32.
I have also tried the overwrite full erase option in SD Formatter also with no success.
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I just noticed this in EmuNAND9
EmuNAND: SD is ready
SD storage: unknown filesystem
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this time a different result happened, I have no idea why
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Total SD card size: 3856MB
Unknown or corrupt file system
Already formatted for EmuNAND
Press A to format, B to cancel
Writing new master boot record...
Formatting FAT partition
Unknown error/something went wrong here
Format this SD card from your PC first
Then try this again
Complete RedNAND Setup: failed!
Bress B to return, START to reboot.
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This time, the data was retained.
what is strange is that EaseUS partition master reads the SD card as Super Floppy, which I have never seen before.