I export JPEG images from retouched RAW files, using Save for Web. Metadata is set to "All Except Camera Info."
Before retouching, I add extensive metadata to the RAW files, including text to the dc:description field. Unfortunately, that one field is stripped out during SFW export. As far as I can tell, no other metadata is stripped from dc namespace.
Please do not tell me to use Export or Save As. Any such answer is off-topic and not helpful. I just want to report this bug (assuming it won't be fixed, though.)