After a Pano merge of several raw images, the time zone is shifted on the merged dng image so it is different from the original raw (Nikon D850 nef) images in the stack. This results in the stack being moved to a different place in the grid sorted by capture date and it seems at first like the images are lost.
I shoot with UTC time zone in camera (so I don't have to keep changing time zones on travel). I keep that UTC for my catalogues. In the several cases that this problem occurred images were shot in Central Asia (UTC +5) and LR CC pano merge shifted the time by -5 hrs for the merged image as if it were trying to force it to UTC, when it was already set that way, apparently based on the GPS location stored in the image.
Always happens, I believe. This does not happen with a merge done in LR Classic, only in LR CC, apparently. Version 2.3.