A few days ago I started completing some of the older triumphs that I hadn't touched just for the fun of it and started working on the Ether Harvest triumph. However, after activating and then completing the heroic event, the chest would say "Required Event Participation" even after I had literally killed the boss solo. I have had this happen twice now (once just today). I am doing the event on the tangled shore and have not seen if the issue is happening elsewhere. I am still getting triumph progression with the ether balls being destroyed, so it isn't stopping triumph progression. The first time I did it, I thought I had stepped away from the event too far, but the second time I was using anarchy and shotguns to damage (aka I was right next to the boss and definitely didn't leave the area). Hopefully it gets fixed and/or this post at least helps. Edit: It happened a third time, so this doesn't seem like a one-off thing, I should also clarify that I was specifically in Four-horn Gulch (I don't recall if there are multiple spawns on the tangled shore for the ether ritual public event). I also completed the triumph I was going for, so you probably won't get anymore updates, but this was just so that other people know and/or to bring it up to bungie devs to try and get it fixed. Anyways happy grinding!