Sounds pretty much like how I roll with my Android "junk" too. It worked for a while, and somewhere down the road in the GO-ville history of crummy updates it no longer does.
Fwiw, I just tried the new GO 4.10 in the S6 and it always says Disconnected too. Default opening is to the Spark, and I noticed they also removed the Inspire 1 as well which it used to boot to. In prior versions of GO 4, it might take 10 minutes before the GO would connect to the P4. Seems to get stuck on charging rather than using the data connection until it decides to change...whenever.
Personally, I would take Android and toss it in the junk and never use with GO. Java isn't playing nice with it and maybe why Apple uses less of that. The Apple iPad
Air 2 I have always connects, albeit the video lag is beginning to show up in it too as GO 4 grows. Probably will need an iPad Pro later this year with GO 4.5 version.
Also, I noticed in my old Samsung tablet GO 4 will randomly try and connect to to the internet at odd times and fail without me wanting to even use it. GO 4 seems to have gotten into the randomware and background-running operating mode now as much of the Android crap. It wants to send out some failure log file when it does fail too. Android is just a mess and why they allow other manufactures (i.e. Samsung.) to further butcher it up is nuts. DJI - and anyone contemplating using Android with DJI products - would be better off ditching it if they don't want problems to arise down the road.
Notice too the "Recommended DJI Android" list is shrinking even with more Android devices appearing. They show the S6 as working, but mine isn't anymore. GO grows, and Android shrinks.