Problem: The "Metadata has been changed" status keeps showing up after saving metadata to file. Why?
Although I saved metadata to file several times Lightroom keeps marking them as changed very quickly again.
Even if I delete the xmp and rewrite.
And as far as I can see, LR does actually write changes, because everything's there when I read the metadata from file.
This concerns thousands (yet by far not all) of photos.
LR 6.3 on Windows 7 Professional 64bit
The files are all on local disks, partly on the same SSD as the operating system, partly on a different disk.
LR since at least version 3 has had problems with spurious indications that the metadata has changed. If you've examined some photos and verified that indeed it is getting written back to the files (e.g. that there isn't a permissions problem), then I wouldn't worry about it.
Using the answers above I managed to get rid of the warnings LR issues, simply by changing the setting "Automatically write metadata changes to disk". Once LR had written everything, the warnings did not pop up again, also not after unticking that option again.