DxO Viewpoint has not worked with Photo for some time, so I thought I would try the recently-updated versions of both. DxO 3 installed OK and appeared in my plugins panel. I loaded an image of a skewed notice board and called up the plugin. It loaded fine and I was able to apply the perspective transformations. I clicked on Apply and then Save but the returned image in Photo was exactly the same as before! No perspective change. The standalone program works with no problems.
John