Metadata File Needs To Be Updated not sticking

I have a large number of photos in my LR catalog with the down arrow icon indicating metadata needs to be written to files. However, when I select files and attempt to write metadata to the files, much of the time at least some of the files still have the down arrow icon, whether or not the .xmp file (or TIFF or JPEG) was actually updated. Attached video shows what happens with a small selection of files. Metadata selection panel shows files need to be updated. I hit Ctrl-S to update and LR appears to be updating. Then the files show right back up again, with the down arrow.

LR 12.1 release, Build [202212702312-d7ab524b] on Windows 10 (although the problem has existed through many versions)