I have Litchi app and Dji go 2.9.1 and version 1.8.10. I have had good luck with flying under Dji go and even ok after the 3.1.2. I just got scared, about all the fly always from it.. So went down to 2.91 . Now I have Litchi on, and using.. Love It! Fun to draw a line, of the route, right before you want to fly, and even days before.. Cool.

Anyway.  I started the Litchi app, after all the drone and control are on. But it kept on saying (disconnected) waited and waited.. even restarted it.. but still. So closed it. Started Dji Go.  Says good for flight. So closed it. And started Litchi app.. it. And all was a go.. I did that like 4 times on the same day. That was yesterday, and today, went out today and no problem. Like normal.

I guess bottom line. You can have both apps on phone. Guess just don’t open both at the same time. Read some where, that you are suppose to force stop dji go app. But don’t think that is necessary.

And I have the Phantom 3 standard. Over 15 hours of flight time and 50 plus miles on it. No major crashes, just damange propes. So have had good luck with it.. Even flew it out 1600 feet over the ocean. And with the Litchi app.. Had the drone out 3500 feet, with no lost sig.  But was out over a open field. The waypoint route flight is very Cool.. Still Learning

DJI Go takes up the default app to fly the P3S, you must force stop it in settings-apps or you are just asking for issues. This procedure is published by Litchi and is part of the initial Warning/Instruction pop up when Litchi is started on your device.

You MUST "force stop" either application before starting the other one. I practice always stopping both of them to start with, then when you start with one and want to switch, be sure you stop the one you were using, not just close it, before you open the other app. There are specific instructions on the Litchi web site about this. The two do not like sharing in the background and you could have some serious problems by not following these guidelines.

Adding to posts above - I assume we're talking Android here.

You can have both Litchi and GO installed at the same time, but shouldn't run them at the same time (which you can with iOS) as it's like a car with 2 steering wheels. On Android though, you need to ensure that the USB port is not assigned to either app as a default - perhaps that's what you're seeing?

On iOS, GO appears to be sensitive to which is installed first (or updated most recently). Solved by re-installing GO afresh. Litchi doesn't have this issue.