RemixOS SD read-only? (OS X)

[jimmyadaro]

Hi there;

I have Pine64+ (2GB) plus the official 16GB SD card with Remix OS. It works excelent.
Now I'm trying to format the SD in order to boot from an external HDD.


I'm using macOs Sierra 10.12.3 (MBP 15-inch early 2011) - when I insert the SD with the SD adapter in the built-in MBP SD reader the OS throws this error:

The disk you inserted was not readable by this computer.

If I open the Terminal and type: 

Code:

diskutil list

it shows this:

Code:

/dev/disk3 (internal, physical):
  #:                       TYPE NAME                    SIZE       IDENTIFIER
  0:                                                   *16.1 GB    disk3

So I installed SDFormatter for Mac, and then it throw this error when I tried to format the SD:

The card is write-protected.
Please release the write protect switch.

BUT the SD adapter is not locked (lateral switch).

So, which may be the issue? The SD card? Mac OS?

Thanks for reading!