I used the feature in Android Marshmallow, format SD card as internal, and I have 3 devices all the same feature available.
after a while I made a factory reset for the devices, and the SD card is not supported and can't be formatted in android device.
I tried using the diskpart in windows, and after "create partition primary" it shows "virtual disk service error the operation is not supported on a non-empty removable disk".
I tried using MiniTool Partition Wizard, but it shows bad disk and after re-inserting the SD card shown nothing was done.
disk management in windows with no use.
what I understood that the android feature make two partitions, 16MB partition and another one for the rest storage which only readable within the android device made it (encrypted some how).