I like to have keywords (tags) stored in my JPG files. Many of my photos have both a CR2 and a JPG version, and many are only JPG. If I add tags to the JPG-only files, the tags are stored in the EXIF data in the JPG file itself. (Good) I can use Windows File Explorer to see the actual tag data. But if the file has both a CR2 and JPG version, a side car file (XMP file) is created for BOTH of them. The tags are NOT store in the JPG file, and, of course, are not displayed by Windows File Explorer. (Not good) How can I get the tags stored inside a JPG file if there is an existing CR2 file for the same photo?
If you have NOT selected the option "Treat JPG files next to RAW as separate photos", Lightroom will not do this. You can use the freeware Exiftool to copy the metadata to the JPGs.
it is my understanding that if you turn on this option, the metadata should be written to the JPGs, but I have not tried it.