MPU9250 magnometer always reading zeros

Hello,
I have two different platforms, an TI OMAP4 and a Qualcomm 8074. Both are running the same version of android and the kernel.
I have the same version of motionapps integrated into both platforms, the only change I had to make was to add support for the devicetree on the 8074.
Installed the SensorSimple app and ran it. On the OMAP, gyro, accel and mag all work. On the 8074, only the gyro and accel work, the mag data is all zero.
I can see the compass being initialized during bootup and if I run the selftest, the mag is access in bypass mode and the test passes.
I've tried multiple chips and the same chip on both platforms so it's not a chip issue.

This seems a bit odd and I'm not sure what could be happening to cause this kind of behaviour. Anybody seen anything like this or have any suggestions?

One more question, when running in normal or non-bypass mode, and accessing teh magnometer should I see activity on the external i2c bus?

thanks,
jeff