Photoshop Elements questions should be posted in the Adobe Photoshop Elements Forum. Somehow your thread got posted in the Adobe Premiere Elements Forum (video editing).
You can re-post your thread in the Adobe Photoshop Elements Forum or wait for a moderator here to see your thread here and move it from here to there.
My opinion on this....from the Photoshop Elements perspective...
Nikon D810 is supported by Camera Raw 8.6 and higher (latest version of Camera Raw is 8.7)
At the same time, the Camera Raw version needs to be supported by the Photoshop Elements version.
Photoshop Elements 12 appears to support Camera Raw up to 8.5 which does not support the Nikon D810.
a. switch to Photoshop Elements 13 (comes with Camera Raw 8.6 and can be updated to 8.7).
b. use the DNG Converter in Photoshop Elements 12