On the Inspire 1 X5 there are TWO switches for AF. One is a hard switch on the camera itself. The other is in software. In the Go App it's in the upper-right hand corner. I don't know where it is with whichever app the Inspire 2 uses. Obviously, you want to make sure that both of those switches are set to AF.
Pro Tip: For 99% of my shooting the subject is outside the ∞ area. So I just set focus MANUALLY on a far-away subject and leave it there. AF has NOT been my friend. SLIGHTLY out of focus isn't seen until you get home on a good monitor. I also use Focus Assist.
What are you shooting? Close ups or anything over 15'? I believe the infinity focus is about 15' from the lens. So just set in manual at infinity in most cases.