You are able to click on the Svergan’s Belongings to drop them into the Soul Pyre, but once you click it nothing actually happens. Bottom right of screen displays that an action is taking place, however you never actually are able to drop belongings in. After 30 sec. CD you are able to attempt again with the same result.
UPDATE: Uhhh… well, some horde came along and a Tauren had the same issue I did… then a Nightborne came thru, did it with ease, bad guy npcs started running into the room so I decided to jump in and kill npcs… lo and behold I was instantly given the end of the quest to turn in…