I've noticed this for a while now. If I try to import from Lightroom and select convert to DNG on import, none of the photos autorotate. For example pictures taken in portrait with the camera are displayed in landscape, it's like the metadata is lost or ignored. This is not an issue if I don't convert to DNG. I've been using Lightroom about 10 years and this is only something I've noticed in recent versions. I'm currently using a Nikon D750 on Mac 10.14.