Just registered to answer you.
I got the same problem with 2 of my SDXC cards from SanDisk 64 GB. The suddenly stopped working after a couple of months, but I was able to access all files.
Tried with Low Level HDD formatter, SDFormatter 4, Gparted, Testdisk 7.1, RescPhoto, gparted on RescueDisk. Different PCs and card readers. NTFS, extFAT, doesn’t matter. Different readers, adapters … nothing helps.
SDFormatter shows the SDXC is write protected, the low level formatter Tool goes through the whole process formatting (2 hours), completes, but nothing happens, Testdisk and gparted shows I/O error, testdisk is showing attribute setting error. Same with formatting under Windows.
If you access the files and right click you don’t even see the context menu “Delete” at all. Properties of the files show “Write protected” and removing the flag doesn’t help (I/O error). And no, I didn’t have the write lock on in the adapter.
The only solution: copy your files to your PC as fast as possible, spend 10 bucks more and get a SD card from a vendor which really cares. I’m using 3x Transcend SDXC 10 UHS-1 64GB in a GoPro and 2 Phones without any problems!
