external speaker feature doesnt work on galaxy ace 3 s7272 duous running CM11 4.4.4

I just installed CM11 4.4.4 on my galaxy ace 3 gt s7272 (duous) , the version is stable but there's some few bugs including that external speaker doesnt work on phone calls, it keeps working on the internal speaker regardless of hitting the speaker button. it works fine on skype and other apps just not the phone.