So I put one of our spare  I-phones on the controller, instead of my android based phones. Works perfectly. So it seems that it's a concoct between the DJI equipment and android based equipment. I've tried several different android phones and it will not work. I put any I-phone on it and it works fine. DJI needs to fix this issue, because I really HATE having to use I-phone product just to fly my drone, as I do NOT like I-phones. So if you have android, I would consider not getting a spark as it just may not work for ya!

djiuser_XfodvkCf2OTX Posted at 1-10 13:18
So I put one of our spare  I-phones on the controller, instead of my android based phones. Works perfectly. So it seems that it's a concoct between the DJI equipment and android based equipment. I've tried several different android phones and it will not work. I put any I-phone on it and it works fine. DJI needs to fix this issue, because I really HATE having to use I-phone product just to fly my drone, as I do NOT like I-phones. So if you have android, I would consider not getting a spark as it just may not work for ya!

I've had the same experience as you regarding Android vs Iphone.  I've been using a Samsung Galaxy S7 as my primary flight display since I started flying my Spark in August, over that time I've had the app crash about 6 or 7 times but I've always been able to get the Spark back home by relaunching the app and flying it home.  One of the bad things is when that happens (other than not being able to see what's going on with the drone) it doesn't record that flight into the flight log (for those that care about those things) .  On one flight more recently the app crashed three times on the same flight.  Since then I switched to my wife's Ipad and have had no issues.  

there was a recent update to the Go4 app on android, I don't know if it solved the Android app problems or not.