Our home has some portions of the back and a small section on one side with the “masonite” siding like yours. The rear of the house faces north which holds a lot of moisture. That type siding is difficult to keep calked and water always finds a way inside. Hardy has an identical size beaded hardy plank siding and I would replace at least the sections that are damaged with Hardy. This stuff does not change during weather variation. I used aluminum calked from behind at each joint and it is much improved. All has now been replaced with Hardy except a gable end with a Single story roof line underneath. Just too scared to work off scaffolding to replace that section!