I ran a quick test, and I conclude that the Aries' (same as DG's) engines are too powerful for a full throttle ascent with the assistance of PEG on the Moon. Whenever you see the crosshair wobbling, it means that PEG lost its convergence, and you need to throttle down smoothly, until the crosshair reappears in a correct position (like 30* higher), and continues its smooth descent. For an orbit of 50x50 km, I had to throttle down to 10%.
This is normal, because PEG assumes keeping engines on all the time until reaching orbit. There's no place for cutting them and circularizing later. This special requirement imposes limitations on the maximal power of engines, or you eject your craft from orbit, like you noticed. Keep in mind that there's a spectrum of engine power that guarantees convergence. You have to experimentally check what is the spectrum's range, by smoothly controlling the thrust.
The DA is quite similar in this regard, where the spectrum regards both PEG and synchronization phase, which in this case means a spectrum or allowed relative inclinations before the injection burn. Too small is also bad. We can get to it later.
PS. There are two crosshairs, because you might choose a northern or southern orbit with the same inclination. Once you setup a target, there's no choice anymore.
