I am a bit confused as to what the question is.
1. Are you saying that you processed the image in NX-D and then trying to open it in Elements.
2. Are you trying to use NX-D from within Elements.
As such I use only NX-D and it gives me no trouble. At times it takes time to open up due to
. NX-D will access and sort all the images in the sub directory, the first time it accesses the directory. If it has generated sidecar files it will read them also. That takes a lot of time, especially if there are more than 100 images.
. NX-D does pre processing on the images to display them to the camera settings.
. If NR, Distortion and other operations are set in camera, NX-D will apply them.
Till it has finished all the operations on every file in the sub directory, the blue circle will spin. In view of the initial overhead of this software, it is better to have the files arranged in sub directories. My images are one sub directory per day, but then I rarely shoot more than 100 images per day.