When completing the Echo Chamber Strike in the Siva strike playlist or just completing it on 320 light the skeleton chest spawns on the other side of an invisible wall barrier. So please either remove this wall or move the chest into a reachable spot.
Bungie is aware of this issue and they are investigating. For more information on this issue and other known issues, please visit this thread: https://www.bungie.net/en/Forum/Post/213318340/0/0[quote][b]Echo Chamber[/b]
We are investigating an issue where player may not be able to access the Hoard Chest after completing the Echo Chamber strike.[/quote]