I am playing tribalist with anointed firestarter, currently fighting in Eternity’s End (I didn’t notice the bug here described in The Barrens, so maybe location matters). Note that I didn’t experience this issue when playing with pyromancer and neither when playing inquisitor (with firestarter anointed).
The bug is that creatures with protected buff are not affected by the firestarter anointment. Proof is that neither inspection nor the buff bar shows the debuff.
EDIT: this issue doesn’t seem to happen 100% of the time though.
Just in case, these are the realm properties.