I have an Inspire 2 and a Phantom 3 Pro. I use the same tablet for both of them , so I have DJI Go and DJI Go 4 installed on the same tablet.

I'm not sure if that is the reason for this issue, but every time I turn on my Phantom 3 controller and then the aircraft, the app does not recognize it.  The light on the controller turns green and I can pan the camera (might be able to take off), but the app does not recognize it until I completely do a relink on the controller.

Any ideas?  Is there an issue with having DJIGO and GO4 installed on the same tablet? Thanks

Just to clarify, does this happen whether or not you connect the craft to either app?

I've never tried connecting my Phantom 3 to the DJi Go4 app as I didn't think that was supported.  It doesn't seem to happen with my Inspire 2/DJI GO 4 though.

My problem is a little worse on my P3Pro. I flew it a few days ago shooting  video after  after 4/18/16...no sweat. Now it will not connect but still flies. what happened ?   Today when i hit ABOUT, all I get is 3.15.1      I get no other update numbers. Dave Doll

I was using a Galaxy Tab A, which technically I guess is not supported by DJI. I went ahead and got an ipad mini 4, which so far seems to work much better. Seems DJI has also put in more dev for the IOS app vs Android (emulator etc..). Thanks

I have same issue at random times with my P3P and Samsung Tab A tablet, I think what's happening is the RC and the quad itself are pairing correctly but the DJI go app isn't always registering/seeing the connection. All I normally do is close the app, unplug the USB cable and plug it back in and this works sometimes. Other times I've only had to power down the quad itself and then start it up again and the app then connects, no sequence seems to be 100% at getting it right every time.

But it has always worked one way or another with a bit of trail and error fiddling, all items on latest firmware. I'm a new owner and have no experience with previous firmware having only had the quad for a week, can't comment on if older firmware was more stable or if it's a new problem. It may even be a compatibility issue as I'm using android devices, not an iOS user.

RC and quad are the only things that need pairing. The tablet is another story. Try a diff cable, make sure usb debugging is on on Android. Try to remember if either the OS on the tablet updated, or perhaps the GO app updated the RC firmware, but u did not follow with updating the aircraft? (although that would usually cause the radio not to connect either, so a red LED on the controller, and no control over the craft.
Try to exit go app, with everything else on, then disconnect and reconnect the cable, see if the app comes up - sometimes the usb port on the radio could go bad? Let's see - what else do I recall...  Ah, sync all your flight logs to dji cloud,m then remove the go app, reboot your tablet, install the app again. If u can, wiping the tablet may be good too, clearing some caches? Once u r back, your records can be synced back from the cloud.
Things like that.... Definitely another USB cable would be one of the first things i'd try.
Ah, once u boot your android device.. give it good 10 min to stabilise.. i've noticed services act funny...
Oh, also, if u got litchi, or any other flying app for dji, remove it! At least while testing! I have tried left and right, and while Litchi was installed, even though I kept killing services, I had disconnects and other issues all the time! Now I got GO on the tablet and  litchi on my phone. Total separation.

I switched to an iPad 4 mini... problem solved.