When opening Double/Large Chests, if they were renamed through an Anvil, they won't display their custom name and instead only show "Large Chest" as their name.

This problem also affects Large Trapped Chests, but does not affect any one-block containers such as Dispensers, Hoppers, Barrels, and single-block Chests.

When breaking the Large Chest and put back into the player's inventory, they'll be shown to retain their custom name rather than resetting to default like other blocks would, indicating this to be merely a display issue rather than the container losing its custom name.