We, 36 of us, are using iPhone 6S Plus. iOS is the latest 11.2.6. But I have noticed the issue ever since the changes last summer, 2016 with the iOS and Explorer for ArcGIS. I am attaching where it locks up, which is right after you choose one of the selections below. I can get this to lock up on any address in the Phoenix AZ metropolitan area. In this example I spoke 2133 west emelita ave clicked the first, highlighted, option, and it lock up every time. You can try 123 oak st for ease of testing and pick either the Chandler or Gilbert AZ options and Explore for ArcGIS locks up on me every single time. I went to one of our other departments who are using iPhone 6 or 6S and was able to replicate the issue. I got a model number of MN1M2LL/A off his phone in hopes that that would tell you if it is a 6 or a 6S. Thanks