Hey, I know I'm late to the party but I have the same issue as well when it comes to charging the ROG Ally. However, I may have found a fix for this and I have a hunch on how it started on mine. It may be different for both your cases. To determine if my guess is right, before this started, did you turn on the 'Sleep Care' and 'Quick Charge' function on the MyAsus app before this happened? Mine started acting up after doing this. So the solution I had to sort of fixing it is this. I open the MyAsus app, toggle both options a few times and eventually leaving both off before exiting the app. I then shut down the ally. After the complete shut down, I plug in the charger before turning it on and after a few seconds after booting, it charged again. It's still finicky hence me saying that I sort of fixed it. This would mean that it's a software issue on the MyAsus app.