I am having a problem with connecting my Mavic to the DJI Go 4 app. It's a Samsung Galaxy Tab A with the latest updates, USB debugging on and MTP enabled. I have tried reinstalling the app several times. The tablet will connect perfectly on my PC so it isn't dropping out like shown in my video. I have tried every order of powering things on and connecting them to no avail. Has anyone else had this problem?

I cannot try it on my Samsung Note 4 phone because I have a known issue with my USB port so it isn't even recognized by the RC. I will note that I connected fine on my friends iPhone 5S. I will try another Android device over the weekend but it just doesn't seem to me like it's a problem with my tablet since both of my PCs do not have a problem connecting to it.

Here is a short video of what it is doing:

https://www.youtube.com/watch?v=cMGlJHFYFW4

My tab a didn't connect bought a shield

Try turning off screen rotation and start the app when the tablet is in landscape (not portrait as in your video). The app can't run in portrait as the screen layout would not fit properly.
I had a similar issue on an android phone. I now have an ipad mini and the app automatically starts in landscape.

Fact is: DJI GO 4 gets more crappy and buggy with each update. It´s not a problem of Your Sammy-tab, it´s a problem with DJI GO 4 programming ...................... {:4_154:}

It's amazing all the problems we're having with this app crashing, 4 times it crashed on me yesterday in one flight, I'm sure most other companies would have sorted it by now as customers get more and more frustrated, it needs sorting or sack the whole coding team.

Like I've said before, this app isn't a game, it controls what in effect could be a very dangerous piece of tech, what if the app crashes at a vital moment and you lose sight of what you're doing causing the Mavic to crash into someone or a car or anything, at the very least you damage a very expensive drone, at the most you cause serious damage to an animal or human being.

GET IT SORTED DJI, this is beyond a joke.

Was having the same problem with both my Galaxy 6 Edge & HTC One M9.  Try using the bottom USB port & see if it stays connected.   That corrected mine from continually disconnecting.   I think my issue is the small cable that connects to the upper port may be bad.

I'm still not sold that it isn't a problem with the app itself on the Tab A but I did get it working on my wifes Samsung Galaxy S7 so I'll just fly with it for now until I decide what I want to do about a new phone for myself. I really don't want to go to Apple but it seems like DJI spends a lot more time polishing the iOS app compared to the Android counterpart. Pretty unfortunate...