Photoshop Elements 18 photomerge panorama not blending images

I am using Adobe Photoshop Elements Version: 18.0 (20201207.m.154403) x64.  I am trying to create a panorama from 5 or 6 originals using Photomerge Panorama in Guided mode.  I enable the setting "Blend images together".  This used to make a layer mask on each layer of the result to prevent seams from being visible in the final image.  Today, I cannot get that to work.  I get a merged result, but without layer masks and with visible seams.  I have tried repeating the merge, restarting Photoshop, and rebooting my machine, but the merge still does not have layer masks for a seamless result.  What am I missing? How can I fix this?