Wrong Interaction betw. Frost Nexus and Skills freezing monsters via Tul's Stillness

Hello, I've been building a chaos dmg build with Tul's stillness for freezing - I noticed that once the skill also has frost nexus socketed on, while the chill ground triggers, no enemy suffers from the "chill" de-buff while they run over said area.

Additionally, I see "chill" tag on Jade Isle boss ONLY, and I also get "self chilled" during simulacrum run. Not sure what's going on here but would like a look if possible, thanks!