What about putting the Monterra in USB debugging mode under Developer Options?
This is not USB Mass Storage Mode.
I suppose not, but it's easy to get gpx files on to the internal and external cards that way.
In other news, I've never seen better than 20 meter accuracy in clear and open sky on my new Monterra and it takes minutes to get a first position fix. My old Montana and even my Nexus 7 V2 can do 3 meter accuracy in 10 or 15 seconds, and even indoors with a couple of north/south facing windows near. That doesn't seem right.
