I'm experiencing the similar issues, though I flashed over a ASOP Rom that has parts from cm10.1 though the Rom was ported from Verizon, but 4g worked perfectly fine, then when I flashed back to cm10 it stopped working. I'm debating on flashing back to that rom and see if it also does not have access to 4g at this time.
Edit/Update: I flashed back to my stock rom with root then flashed an updated MA6 Rom, updated the PRL, Profile and such, still no 4G. Decided that I'd mess with a few 4g settings, still problems. Then I flashed back to CM10 and my 4G works again.