I have the same symptoms as you. I have mine connected to an APM1.4 and the power light comes on, but, like you, the fix light stays off. I have installed the Ublox GUI and can see packet transmissions from the LEA-6, but it cannot get a fix either inside nor outside.
How did you resolve your issue with your LEA-6?
It turned out to be a defective unit. I sent it back to 3DR and they just shipped the replacement. Took a couple weeks, but it is on the way.
OK - got the new unit and am seeing the same thing. If I use my external MediaTek, with the same cable it locks withing a few minutes. With the UBlox. Nothing after two hours. Going to try to figure out how to conenct it to the PC and see if it is working at all. Can't see how the APM would work with the one but not the other. On Mediatek, teh Planner shows the GPS is attached and the lock comes pretty quickly (<5 minutes first time and sub one minute after with battery backup). With UBlox, planner shows GPS attached, but never shows anything except 0 satellites and 100 HDOP and no lock.
I have the same problem. As they mentioned in 3D robotics, the LEA-6 doesn't need any configuration and it should be plug-and-play. Mt UBLOX GPS doesn't work at all. Do you recommend to contact 3D robotics for replacement?