Have found two hidden secret chests in Arch Haven dungeon.  The chests are located on islands just off the bridge in the second area of the dungeon.  Rolling gets the chests to appear and getting credit for finding the secret.  However, there does not appear to be anyway to actually get to and open the chests.

Is this a bug, oversight or missing something?

Several Youtubers have posted various attempts to get to these chests with no success either.