i got the same problem in this and cMIUI roms... I found a work around though, istall ICS binder from the market them follow this..
http://forum.xda-developers.com/showpost.php?p=32334300&postcount=309
reboot, give it a couple of minutes and walla!
Hope it helps
Interestingly, I have been using cMIUI/Fluxi as my primary rom/kernel for quite a while now, having never experienced this issue. I decided to give this one a try because, as I understand it, cMIUI is no longer being updated.
Not only does my music not show up from my external, but when I plug my phone in my computer, it doesn't even mount. It only mounts the internal SD.
I did some googling and I actually came across the ICS Binder. In fact,
that exact thread you were kind enough to link for me. Unfortuantely, it didn't solve the problem. I think because that related to ICS, not Jellybean. Unless I had a setting wrong, the setting in the screenshot provided is not an option.
I noticed though, reading
that thread, that the member
Zimaia solved his issue by installing a different Kernel, that being "Dorimanx", which leads me to believe that the issue is with Siyah.
Anyway, I actually went back to cMIUI ICS. Never actually had any real issue with it...
Thanks for taking the time to read this. c:
edit to add: So, curiously I decided to flash Siyah 4.3 (ICS version) to see what would happen. My SD card seemed to have vanished! I flashed back to Fluxi and it magically returned. HAHA, I guess that's that.