I use Navfree, which I find excellent.

Also, have you checked your GPS settings on your Nexus 7?

To control what location information your device can use, go to Settings > Personal > Location Access.

When the Access to my location switch at the top of the screen is On, you can select either or both of these tick boxes:

GPS satellites. Just like a GPS device in your car lets your device calculate your location based on satellite signals.

Wi-Fi & mobile network location. Lets your device use Google's location service to help estimate your location faster, with or without help from GPS.

When the switch is Off, your device can’t find your precise location or share it with any apps.

Problem was solved by rebooting into safe mode (which allowed me to access Settings), and then restoring it to Dalvik. So there is probably a small bug in ART somewhere on this (runs fine on my Nexus 5 with Apex launcher).