Default [Q] Unmountable sdcards after flashing 4.4?

So.. I did what I planned for this weekend - installing the Carbon 4.4.2 rom. ^^
But I have a problem..
In recovery, when I select "Mount USB storage", my computer can detect both the internal storage and the external sdcard. But I can't move files to any of them. I can't even read files.
First, I thought this was a driver issue, but yesterday I noticed that I couldn't move Dolphin Browser's download location to ext sdcard.

It appears that the internal storage is listed twice in the storage directory, while only one of the links is working. The external sd however is listed only once and unfortunately not working.. :/

And by the way, any file managers work just fine. I have full access to the ext sd there..

Hope anyone can help me.

Sent from my Xperia V using Tapatalk.
My work:
  • NeoWave - A fully Z3 themed custom rom for the Sony Xperia V (Link) and Xperia T (Link)