Photoshop Elements Organizer deletes IPTC-Tag CodedCharacterSet when meta-data are stored in file

I have set the PTC-Tag CodedCharacterSet to UTF8 in all my files. Now I changed some tags in Photoshop Elements Organizer and saved the meta-data in the changed files. Then unfortuately the IPTC-Tag has been deleted. Has anyone an explanation why this happens? Is it possible, to change this behavoir?