update, this does not seem to happen every time, but might actually be related to steam Family Share. I changed accounts in order to access the same SP world with another character, which normally will maintain separate ownership of structures per account. It works as expected for build pieces, but the treasure coffers don’t seem to keep their ownership correctly and end up being owned by no one afterwards. You can’t interact with them, but if you “loot all” from the menu you can take the items.