I don't have any Bluetooth issues, here are my tips:
Make sure NO other device is paired to the amp, Unpair and turn off BT for any other device besides the the one you want to pair.
Go into the 'pair' screen of the app, make sure your amp is on, and select it to pair.
If your BT indicator on the AMP is blinking SLOWLY, hold the button for several seconds. You want the blinking light to be blinking FAST, or just staying on. If it turns off, or blinks slowly, let go of it, and hold it again for a few seconds.
This consistently works for me, and I have had no disconnection errors, unless I closed the app or something similar. Usually it will give me the error message a few times, before loading for a longer time, and once it has been loading for a few seconds, I know it will pair. I sometimes open up the menu from the side, just to see and confirm it is pairing.
Let me know if this helps you