I assume that Amnytas would work, too. Apparently non-SotO maps have this issue at the moment. Completing Tier 3 Rift Hunts on non-SotO maps, e. g. Sandswept Isles, also might not progress the Vault Special task to "Complete 15 Tier 3 Rift Hunts". At least they did not for me, though the Commander using the Motivations claimed that they were making progress.