P: Unable to merge the photos. Please cancel and review your selection.

Sound great, but in real terms, what does this mean for me and when can i expect it to work again for me and what , if anything, will i have to do on my side.

The engineers identified the issue and have logged a bug for it. Thanks for reporting and providing sample files.

Very much appreciated

I have forwarded this thread to the Camera Raw team for review since both Camera Raw and Lightroom Pano stitching are affected but Photoshop is not. 

Nothing has changed in the way I shot the ones that work and the ones now that don't anymore. I do a full shift to one side - shoot, then rotate the lens 180 deg. to the other side, rotate the camera back to the upright position - shoot, then shift back to center for the last shot. No tilting involved, although, in the past I have done that too, successfully. Exactly, it worked before????

You're on the right forum for asking. What I do know is that missing lens profiles makes Lightroom complain when doing stitching. And the use of perspective control lenses also complicates it, because Lightroom does not always know how to distort the images to get the perfect match. Maybe these shots were taken with more shift than others? So while I'm not completely surprised that the stitching failed, if it worked before...

Dont think it is the light problem, as i have tested it on other images that are less dynamic. would you have any idea whom i might ask, as i do this for a living and it slows ever shot down having to constantly test the image in PH. and BTW thank you already for your help. the difference between the Nikon and Schneider Krutznacht is it has no electronics at all. but there again, it was working fine before????

I see no clear reason why they would not stitch, but they indeed also don't on my system. Also not in Camera Raw. I suspect that the overexposed bright doors are throwing off the stitching process, but as you've shown, other software (including Photoshop) can deal with that without a problem.

maybe it is a geo political bug

I use Nikon Capture with my D850 tethered to Mac Book Pro and images show up in Lightroom directly. Settings are Image Quality NEF (RAW), FX 36 x 24, RAW Image size Large (8256 x 5504), Lossless Compressed, 14 bit. The 3 images are selected in LR and Control/M keys are clicked on, but merging fails. (images are not edited before in anyway)