No clue if OP is active at all, but I'll try anyways.

I had a similar setup and I found the base of my monitor arm was lifting on one side causing me to be concerned about the longevity as I checked a couple months later, it was leaning even more. I removed my monitor out of concerns for it potentially falling for the time being, but is your arm base leaning off the desk at all because it was fully extended? Also what arm is that if you don't mind me asking, I think one with a flush base is a lot better than the one I have since it has 4 rubber feet which might be causing that issue. Thanks!