I've narrowed it down a bit. If noise suppression and speakerphone are activated simultaneously, I can hear the other party but they cannot hear me.
Also, please don't abandon this ROM
it's the only one I know of that has call recording.
Another thing, more of an inconvenience than anything else (for the time being) is that encryption of storage hangs at 0% completion.
InfoSec expert by day, phone hacker by night