Gray points mean that the tie point has been detected, but was not used for alignment (marked as invalid). So they are not original key points.
Key points are not displayed in the photo view mode.
You may observe similar behavior, if you add completely different random image to the overlapping image set and try to run Align Photos operation - no tie points will be detected on that additional image.
According to the screenshots, the point of view is quite different, are there any other images similar to the one where no tie points are detected?