My opinion on why uConnect app doesn't work
We all know the uConnect app rarely works, and I think I know why. The 4G connection in the van can't be left on all the time, it would drain the 12v battery. So it must wake up on a periodic basis and try to connect, at which time it can receive any requests. My experience with M2M (machine to machine) cellular devices is that they often do not connect quickly. I think many times the van tries to connect and it's too slow. The van then puts the 4G back into dormant mode before it can connect and the app times out. Occasionally you get lucky and the 4g connects fast enough, and you get a response. You're still waiting some amount of time for it to wake up though.
This morning, I started the vehicle so 4G would be on continuously and tried the app for location and vehicle data. It worked every time, and quickly too. This would seem to prove out my theory.