E. g. Sandswept Isles
Today I made some progress (5 Tier 3 Rifts) by joining a commander in Amnytas who was using Rare Motivations to track and open Tier 3 Rifts. Then I joined a squad in Sandswept Isles doing the same thing, but I wasn’t making any more progress towards the task while the commander (who was using the motivations) apparently did. Though I received Tier 3 Essences.
Also, Sandswept Isles did not work for the Rift Hunt Vault Daily Task (a day or two ago) and there is a [merged] bug thread on the forums about various Rift Hunt Reward Issues.