My Samsung Galaxy Tab E powered with Android version 7.1.1 is having trouble recognizing Go Fly.  I have updated DJI Go 4 – For drones since P4 app 4 times.  The DJI Go 4 update was loaded from Google Play store. When I connect the USB cable from the Tablet to the RC unit, a message is displayed to select the USB cable option for about 2 seconds.  About 10 seconds later the message is repeated again for about 2 seconds.  This message repeats continuously until I abandon the DGI Go 4 app.  When I disconnect the USB cable,  the message stops, when I connect the USB cable again the message is displayed for a short time and follows the same repeat pattern. All batteries are charged fully.  The RC unit does find the drone with “Ready to Fly”.  The Samsung Experience version is 8.5. I tried a different USB cable, but no change to the trouble.  

You may try to reinstall the DJI GO 4 app, download the apk file and install it to the mobile device https://www.dji.com/uk/phantom-4-pro/info#downloads.
If it keeps doing so, it could be the compatibility issue of your mobile device and DJI GO 4 app, please try to use a different device. Thank you.

Seems to me that the Tab E is not a supported device for DJI Go 4.