Stack sigils do not work in Crown Pavillion
I haven’t bothered to visit but judging from other people’s post the mobs in there do not give any experience. If a mob doesn’t give experience it won’t give a stack either. This is the same everywhere in the game.
That would make sense. But I could have sworn I was getting stacks from killing mobs in there on Thursday. Although I might just be going mental in light of the spurious stacking changes.
They don’t count as kills for the Daily, so probably don’t count as kills for anything else, either.
Most of the mobs in the Pavilion don’t give XP, so they won’t charge your sigils.
BUT… There are a few odd enemies in there that DO seem to give experience (and drop standard loot). These are ones like the Covington Pirates in Wiggin’s sector, which aren’t Veterans and don’t seem to transform back to Watchknights when they die. These do charge your sigils. Of course, tracking them down in the mess of enemies is usually more trouble than it’s worth.