photo merge error with adobe lightroom classic

I’m trying to use Adobe Lightroom Classic to merge 10x images and although they show up just fine in the Panorama Merge Preview dialog when I click on the “Merge” button in that dialog I get this error:

Photo merge error
Unable to merge the photos.
Failed to import the final merged result from
C:pathtomy imagesfilename-Pano.dng.

I see that filename-Pano.dng is created in that directory with 40.4 MB of data but Adobe Lightroom just isn’t letting me use it.

Any ideas?

I’ve tried restarting Adobe Lightroom Classic without success.