same thing for me, I have missing rewards from scenarios, especialy Samisen is the one interesting me.
Double-check that it isn't already in your collection (B-deck Item). The original set of reward cards just add them to your collection without giving you a free copy you can immediately use.
Otherwise check out the troubleshooting steps below. The game should be scanning for missing reward cards each startup. If one is missing, there might be a scenario that didn't get properly recorded as being completed on Legendary. Otherwise, yeah, you may need to wait for the support team to return from the holidays.
- go on the Adventure screen (where all the Adventure Decks are depicted as locations on a map
- select the Adventure for which your Legendary difficulty Treasure didn't unlock
- start browsing the Adventure's scenarios in the list on the left
- you will probably find that on one or more scenarios
- despite the fact that they're check-marked as completed on Legendary difficulty- , when selected, their default difficulty icon (the one with the skull) will not be red (Legendary) but blue (Normal) or green (Heroic)
- it is most likely these scenarios that are bugging your unlock
- replay these scenarios on Legendary (despite their default difficulty being set to something else, the fact that they're check-marked on the list should mean Legendary difficulty is unlocked, so you won't have to replay the lower difficulties)
In another topic, a player complained about his Samisen not unlocking, so maybe it's a similar issue, and the steps above will probably fix any missing Legendary unlocks, not only Orik's Shield.