Default [Q] How to use GSM SIM on Samsung Galaxy S 4 (Sprint SPH-L720) with 4.4.2 ROM?

Hi, I'm using the phone on GSM network outside the US, it had no problem when on 4.3.

After installing the 4.4.2 ROM (it is Sac's custom ROM based on official 4.4.2) I find it does not work with GSM SIM. There is no APN setting available, mobile network has no GSM option either.

Is there some hidden trick to re-enable GSM support on 4.4? Thank you.