Yeah, it's stupid that certain valuable items can't be vaulted. Of course it's because Bungo wants you to have to stop what you were doing and go grind more garbage content to get more currency so you can do useful things like masterwork exotic armor. Which I do when a piece seems good enough to warrant it. Things like higher-end currencies should be able to be vaulted--I'd give up a few slots in the vault for that. I have stupid numbers of bricks of Mod Components in my vault (and these jokers can't even handle letting us discard such things by the full brick), and I can store Enhancement Cores there, yet I can't put Ascendant Shards, Upgrade Modules, or Enhancement Prisms there.