I'm painting all my walls so I started prepping the surfaces by sanding. When I got to a peaked joint I proceeded to sand it with an electric orbital sander and paint started peeling more and more until it got to this state:
I googled around and found this question: How to prepare wall with peeling paint for painting
From the answer posted, I tried hand sanding the peeling edges but the paint layer is removed at a slower rate than the white material underneath, resulting in the surface dipping at the edge:
Should I proceed to sand with my orbital sander until the paint stops peeling instead? And what would be the best way to fill in this patch?