Default [Q] 64 Gb FAT32 SD card disappeared from Omnirom

Using nightly Omnirom, my SD card was working fine for the past six months, when suddenly mid June or so it just stopped appearing in all file managers, when I plug it in to the PC, seems to have vanished. I tried powering the phone down, removing & re-inserting the card, still nothing. Funny thing is that when I boot into TWRP I can see the card fine, with the files that are supposed to be there. Does anyone have any idea what is going on here? SIlly thing is I lost my little microSD adapter thing, so I cant look at it in a PC.

thanks for any help