Strongbox additional map currency not dropping currency

I've opened cartographers strongbox with "Contains 6 additional Map Currency Items". I received just a map which is a base reward from the strongbox itself, not a single currency item. I do press alt so it's definitely not hidden. While it's not shown on the video, I've returned later on with no filter whatsoever and still didn't see any currency items.

Bug 3,959,664,178

vid: https://www.youtube.com/watch?v=n8L1ryJ0uJw