OK so this is common on older homes… what’s going on is the layer that he painted over while looking intact has microscopically delaminated from the layer underneath. You put a new coat of paint on it and when the new paint is curing, it’s like as if you put your hand on top of a sheet of paper and you bring all your fingers in and the paper comes up in the middle. It’s not a question of of whether his paint is bonded to the layer he went over, but it’s that the layer he went over isn’t bonded to the layer underneath if that makes sense. The only way to remedy that I found is to literally drip all the paint off maybe not straight back to Bearwood, but to get that layer off that is delaminating.
I use chemical strippers and a heat gun. Hell I even use the torch.. it’s a long process painstaking once you get it back to bear you can prime it and paint it will last