I'm pretty sure it's a bug, but the difficulty tier you select is active in group instances. I was doing duo Woe of the Willow today and my Deadly +3 was active while the person I was playing with didn't have a difficulty tier selected. If this isn't a bug, it pretty much means you have to group with people that have around the same difficulty tier.
Edit: So after getting to play around with this more it seems to only be WoE solo which is one / two-person groups in there. Still seems like a bug to me. There is ZERO chance you can do this with deadly +3 as a solo player unless you are way over-leveled.
Edit 2: Got a reply from my bug report that it is intended that solo and duo instances retain the difficulty choice. Kinda weird to call it a landscape difficulty slider if it has an effect on instances.
Last edited by menacer53; Jul 01 2021 at 10:28 AM.