Had this two times now during seperate Chaos Wastes Citadel runs with WARRIOR PRIEST.
I got the Boon, and even if I was way above 75% Health, the icon never showed up, and I never got the typical friendly fire voicelines that go along with it.
WARRIOR PRIEST also had a Problem with exploding Barrels during the event on Foetid Gorge (only had that once), where you have to put the 3 Barrels in place. Everytime I picked one up it immidetaly light up as if I hit it.
Very annoying, did not matter which Weapon I had out, even went down inbetween, still same Problem.
Edit: @FatsharkLev
So just played as FootKnight and Warrior Priest was the host.
Got Lady of the Lake boon, but again the Icon did not show, even when I was at 100% health, and it felt like the effect wasn´t there too.
Maybe that boon interacts badly with something from Warrior Priest?