Drive [Q] Completely removing encryption on SD?

So when I joined my phone to the corporate network, it insisted on (amongst other things), encrypting the SD card. After some annoyance with that, pins etc, I decided to revert back. I successfully removed the accounts etc and unchecked the encrypted SD card option.

However, when I did so, it said something about only applying going forward and I still keep getting asked for the pin to decrypt the SD card. So it seems that stuff is still decrypted on there? I have done some searching but have had little luck finding any definitive answers, most seem to be related to problems with people losing whatever key to decrypt items which is obviously not the case here since once I enter the pin, I can access items with no problem

So what's the deal? Do I have to save everything off and reformat the SD card to get back to normal? Seems kind-of wonky to me but that's Android, I guess.

Oh, I have tried reencrypting and unencrypting the SD card again and the Android version is 4.1.2 if that's any help.