Got the same problem since july on my Xperia ZL.
After some research I noticed that my compass is going nuts, it keeps rotating. So since the phone is not able to detect North, East, South and West, he isn't able to obtain a GPS lock.
You can check that by entering in your dialer : *#*#7378423#*#*
this wil open the Sony Service Menu, go to service test, and there test your compass.
I got the yaw value that keeps increasing to 359, and then restarts from 0, like in this video : https://www.youtube.com/watch?v=l7je_iec...